1000 (number)

{{hatnote|"1,000", "Thousand", and "Chiliad" redirect here. For other uses, see 1000 (disambiguation) or, for the military unit, see Chiliarchy.}}

{{Infobox number

| number = 1000

| divisor = 1, 2, 4, 5, 8, 10, 20, 25, 40, 50, 100, 125, 200, 250, 500, 1000

| roman unicode = M, m, ↀ

| unicode = ↀ

| Greek prefix = chilia

| Latin prefix = milli

| lang1 = Tamil

| lang1 symbol = ௲

| lang2 = Chinese

| lang2 symbol = 千

| lang3 = Punjabi

| lang3 symbol = ੧੦੦੦

|lang4 = Devanagari

| lang4 symbol = १०००

|lang5=Armenian|lang5 symbol=Ռ|lang6=Egyptian hieroglyph|lang6 symbol=𓆼}}

1000 or one thousand is the natural number following 999 and preceding 1001. In most English-speaking countries, it can be written with or without a comma or sometimes a period separating the thousands digit: 1,000.

A group of one thousand units is sometimes known, from Ancient Greek, as a chiliad.{{Cite web|url=https://www.merriam-webster.com/dictionary/chiliad|title=chiliad|publisher=Merriam-Webster | archive-url=https://archive.today/20220325170822/https://www.merriam-webster.com/dictionary/chiliad|archive-date=March 25, 2022|url-status=live}} A period of one thousand years may be known as a chiliad or, more often from Latin, as a millennium. The number 1000 is also sometimes described as a short thousand in medieval contexts where it is necessary to distinguish the Germanic concept of 1200 as a long thousand. It is the first 4-digit integer.

Notation

The decimal representation for one thousand is
1000—a one followed by three zeros, in the general notation;
1 × 10³—in engineering notation, which for this number coincides with:
1 × 10³ exactly—in scientific normalized exponential notation;
1 E+3 exactly—in scientific E notation.
The SI prefix for a thousand units is "kilo-", abbreviated to "k"—for instance, a kilogram or "kg" is a thousand grams. This is sometimes extended to non-SI contexts, such as "ka" (kiloannum) being used as a shorthand for periods of 1000 years. In computer science, however, "kilo-" is used more loosely to mean 2 to the 10th power (1024).
In the SI writing style, a non-breaking space can be used as a thousands separator, i.e., to separate the digits of a number at every power of 1000.
Multiples of thousands are occasionally represented by replacing their last three zeros with the letter "K" or "k": for instance, writing "$30k" for $30 000 or using "Y2K" to denote the Year 2000 computer problem.
A thousand units of currency, especially dollars or pounds, are colloquially called a grand. In the United States, this is sometimes abbreviated with a "G" suffix.

In Mathematics

A chiliagon is a 1000-sided polygon.{{Cite OEIS|A195163|1000-gonal numbers: a(n) equal to n*(499*n - 498)}}

Numbers in the range 1001–1999

= 1001 to 1099 =

1001 = sphenic number (7 × 11 × 13), pentagonal number, pentatope number, palindromic number
1002 = sphenic number, Mertens function zero, abundant number, number of partitions of 22
1003 = the product of some prime p and the p^th prime, namely p = 17.
1004 = heptanacci number{{Cite OEIS|A122189|Heptanacci numbers}}
1005 = Mertens function zero, decagonal pyramidal number{{cite OEIS|A007585|10-gonal (or decagonal) pyramidal numbers}}
1006 = semiprime, product of two distinct isolated primes (2 and 503); unusual number; square-free number; number of compositions (ordered partitions) of 22 into squares; sum of two distinct pentatope numbers (5 and 1001); number of undirected Hamiltonian paths in 4 by 5 square grid graph;{{cite OEIS|A332307|Array read by antidiagonals: T(m,n) is the number of (undirected) Hamiltonian paths in the m X n grid graph|access-date=2023-01-08}} record gap between twin primes;{{cite OEIS|A036063|Increasing gaps among twin primes: size}} number that is the sum of 7 positive 5th powers.{{Cite OEIS|A003352|Numbers that are the sum of 7 positive 5th powers}} In decimal: equidigital number; when turned around, the number looks like a prime, 9001; its cube can be concatenated from other cubes, 1_0_1_8_1_0_8_216 ("_" indicates concatenation, 0 = 0³, 1 = 1³, 8 = 2³, 216 = 6³){{cite OEIS|A061341|A061341 Numbers not ending in 0 whose cubes are concatenations of other cubes}}
1007 = number that is the sum of 8 positive 5th powers{{Cite OEIS|A003353|Numbers that are the sum of 8 positive 5th powers}}
1008 = divisible by the number of primes below it
1009 = smallest four-digit prime, palindromic in bases 11, 15, 19, 24 and 28: (838₁₁, 474₁₅, 2F2₁₉, 1I1₂₄, 181₂₈). It is also a Lucky prime and Chen prime.
1010 = 10³ + 10,{{cite OEIS|A034262|2=a(n) = n^3 + n}} Mertens function zero
1011 = the largest n such that 2ⁿ contains 101 and does not contain 11011, Harshad number in bases 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 (and 202 other bases), number of partitions of 1 into reciprocals of positive integers <= 16 Egyptian fraction{{cite OEIS|A020473|2=Egyptian fractions: number of partitions of 1 into reciprocals of positive integers <= n}}
1012 = ternary number, (32₁₀) quadruple triangular number (triangular number is 253),{{Cite OEIS|A046092|name=4 times triangular numbers: a(n) = 2*n*(n+1)|access-date=2023-10-10}} number of partitions of 1 into reciprocals of positive integers <= 17 Egyptian fraction
1013 = Sophie Germain prime,{{Cite OEIS|A005384|Sophie Germain primes p: 2p+1 is also prime}} centered square number,{{Cite OEIS|A001844|Centered square numbers}} Mertens function zero
1014 = 2¹⁰-10,{{cite OEIS|A000325|2=a(n) = 2^n - n}} Mertens function zero, sum of the nontriangular numbers between successive triangular numbers 78 and 91{{cite OEIS|A006002|2=a(n) = n*(n+1)^2/2}}
1015 = square pyramidal number{{Cite OEIS|A000330|Square pyramidal numbers}}
1016 = member of the Mian–Chowla sequence,{{Cite OEIS|A005282|Mian-Chowla sequence}} stella octangula number, number of surface points on a cube with edge-length 14
1017 = generalized triacontagonal number{{Cite OEIS|A316729|2=Generalized 30-gonal (or triacontagonal) numbers: m*(14*m - 13) with m = 0, +1, -1, +2, -2, +3, -3}}
1018 = Mertens function zero, 1018¹⁶ + 1 is prime{{cite OEIS|A006313|Numbers n such that n^16 + 1 is prime}}
1019 = Sophie Germain prime, safe prime,{{Cite OEIS|A005385|Safe primes p: (p-1)/2 is also prime}} Chen prime
1020 = polydivisible number
1021 = twin prime with 1019. It is also a Lucky prime.
1022 = Friedman number
1023 = sum of five consecutive primes (193 + 197 + 199 + 211 + 223);{{Cite OEIS|A034964|Sums of five consecutive primes}} the number of three-dimensional polycubes with 7 cells;{{Cite OEIS|A000162|Number of 3-dimensional polyominoes (or polycubes) with n cells}} number of elements in a 9-simplex; highest number one can count to on one's fingers using binary; magic number used in Global Positioning System signals.
1024 = 32² = 4⁵ = 2¹⁰, the number of bytes in a kilobyte (in 1999, the IEC coined kibibyte to use for 1024 with kilobyte being 1000, but this convention has not been widely adopted). 1024 is the smallest 4-digit square and also a Friedman number.
1025 = Proth number 2¹⁰ + 1; member of Moser–de Bruijn sequence, because its base-4 representation (100001₄) contains only digits 0 and 1, or it's a sum of distinct powers of 4 (4⁵ + 4⁰); Jacobsthal-Lucas number; hypotenuse of primitive Pythagorean triangle
1026 = sum of two distinct powers of 2 (1024 + 2)
1027 = sum of the squares of the first eight primes; can be written from base 2 to base 18 using only the digits 0 to 9.
1028 = sum of totient function for first 58 integers; can be written from base 2 to base 18 using only the digits 0 to 9; number of primes <= 2¹³.{{cite OEIS|A007053|2=Number of primes <= 2^n}}
1029 = can be written from base 2 to base 18 using only the digits 0 to 9.
1030 = generalized heptagonal number
1031 = exponent and number of ones for the fifth base-10 repunit prime,{{Cite OEIS|A004023|Indices of prime repunits: numbers n such that 11...111 (with n 1's)... is prime}} Sophie Germain prime, super-prime, Chen prime
1032 = sum of two distinct powers of 2 (1024 + 8)
1033 = emirp, twin prime with 1031
1034 = sum of 12 positive 9th powers{{Cite OEIS|A004801|Sum of 12 positive 9th powers}}
1035 = 45th triangular number,{{Cite OEIS|A000217|Triangular numbers}} hexagonal number{{Cite OEIS|A000384|Hexagonal numbers}}
1036 = central polygonal number{{Cite OEIS|A000124|Central polygonal numbers (the Lazy Caterer's sequence): n(n+1)/2 + 1; or, maximal number of pieces formed when slicing a pancake with n cuts }}
1037 = number in E-toothpick sequence{{Cite OEIS|A161328|name=E-toothpick sequence (see Comments lines for definition)}}
1038 = even integer that is an unordered sum of two primes in exactly n ways{{Cite OEIS|A023036|Smallest positive even integer that is an unordered sum of two primes in exactly n ways}}
1039 = prime of the form 8n+7,{{Cite OEIS|A007522|Primes of the form 8n+7, that is, primes congruent to -1 mod 8|access-date=2023-10-10}} number of partitions of 30 that do not contain 1 as a part,{{cite OEIS|A002865|Number of partitions of n that do not contain 1 as a part}} Chen prime, Lucky prime
1040 = 4⁵ + 4²: sum of distinct powers of 4.{{Cite OEIS|A000695|Moser-de Bruijn sequence: sums of distinct powers of 4}} The number of pieces that could be seen in a 6 × 6 × 6× 6 Rubik's Tesseract.
1041 = sum of 11 positive 5th powers{{Cite OEIS|A003356|Numbers that are the sum of 11 positive 5th powers}}
1042 = sum of 12 positive 5th powers{{Cite OEIS|A003357|Numbers that are the sum of 12 positive 5th powers}}
1043 = number whose sum of even digits and sum of odd digits are even{{Cite OEIS|A036301|Numbers whose sum of even digits and sum of odd digits are equal}}
1044 = sum of distinct powers of 4
1045 = octagonal number{{Cite OEIS|A000567|Octagonal numbers: n*(3*n-2). Also called star numbers}}
1046 = coefficient of f(q) (3rd order mock theta function){{Cite OEIS|A000025|Coefficients of the 3rd-order mock theta function f(q)}}
1047 = number of ways to split a strict composition of 18 into contiguous subsequences that have the same sum{{Cite OEIS|A336130|Number of ways to split a strict composition of n into contiguous subsequences all having the same sum}}
1048 = number of partitions of 27 into squarefree parts{{Cite OEIS|A073576|Number of partitions of n into squarefree parts}}
1049 = Sophie Germain prime, highly cototient number,{{Cite OEIS|A100827|Highly cototient numbers: records for a(n) in A063741}} Chen prime
1050 = 1050₈ to decimal becomes a pronic number (552₁₀),{{cite web | url=https://www.rapidtables.com/convert/number/base-converter.html?x=1050&sel1=3&sel2=10 | title=Base converter {{pipe}} number conversion }} number of parts in all partitions of 29 into distinct parts{{cite OEIS|A015723|Number of parts in all partitions of n into distinct parts}}
1051 = centered pentagonal number,{{Cite OEIS|A005891|Centered pentagonal numbers}} centered decagonal number
1052 = sum of 9 positive 6th powers{{Cite OEIS|A003365|Numbers that are the sum of 9 positive 6th powers}}
1053 = triangular matchstick number
1054 = centered triangular number{{Cite OEIS|A005448|2= Centered triangular numbers: a(n) = 3*n*(n-1)/2 + 1}}
1055 = sum of 12 positive 6th powers{{Cite OEIS|A003368|Numbers that are the sum of 12 positive 6th powers}}
1056 = pronic number{{Cite OEIS|A002378|Oblong (or promic, pronic, or heteromecic) numbers}}
1057 = central polygonal number{{Cite OEIS|A002061|2=Central polygonal numbers: a(n) = n^2 - n + 1}}
1058 = sum of 4 positive 5th powers,{{Cite OEIS|A003349|Numbers that are the sum of 4 positive 5th powers}} area of a square with diagonal 46{{cite OEIS|A001105|2=a(n) = 2*n^2}}
1059 = number n such that n⁴ is written in the form of a sum of four positive 4th powers{{Cite OEIS|A003294|Numbers k such that k^4 can be written as a sum of four positive 4th powers}}
1060 = sum of the first twenty-five primes from 2 through 97 (the number of primes less than 100),{{Cite OEIS|A007504|Sum of the first n primes}} and sixth sum of 10 consecutive primes, starting with 23 through 131.{{Cite OEIS|A127337|Numbers that are the sum of 10 consecutive primes}}
1061 = emirp, twin prime with 1063, number of prime numbers between 1000 and 10000 (or, number of four-digit primes in decimal representation){{Cite OEIS|A006879|Number of primes with n digits.}}
1062 = number that is not the sum of two palindromes{{Cite OEIS|A035137|Numbers that are not the sum of 2 palindromes (where 0 is considered a palindrome)}}
1063 = super-prime, sum of seven consecutive primes (137 + 139 + 149 + 151 + 157 + 163 + 167); near-wall-sun-sun prime.{{Cite OEIS|A347565|Primes p such that A241014(A000720(p)) is +1 or -1}} It is also a twin prime with 1061.
1064 = sum of two positive cubes{{Cite OEIS|A003325|Numbers that are the sum of 2 positive cubes}}
1065 = generalized duodecagonal{{Cite OEIS|A195162|2=Generalized 12-gonal numbers: k*(5*k-4) for k = 0, +-1, +-2, ...}}
1066 = number whose sum of their divisors is a square{{Cite OEIS|A006532|Numbers whose sum of divisors is a square}}
1067 = number of strict integer partitions of 45 in which are empty or have smallest part not dividing the other ones{{Cite OEIS|A341450|Number of strict integer partitions of n that are empty or have smallest part not dividing all the others}}
1068 = number that is the sum of 7 positive 5th powers, total number of parts in all partitions of 15{{cite OEIS|A006128|Total number of parts in all partitions of n. Also, sum of largest parts of all partitions of n}}
1069 = emirp{{Cite OEIS|A006567|Emirps (primes whose reversal is a different prime)}}
1070 = number that is the sum of 9 positive 5th powers{{Cite OEIS|A003354|Numbers that are the sum of 9 positive 5th powers}}
1071 = heptagonal number{{Cite OEIS|A000566|Heptagonal numbers (or 7-gonal numbers): n*(5*n-3)/2}}
1072 = centered heptagonal number{{Cite OEIS|A069099|Centered heptagonal numbers}}
1073 = number that is the sum of 12 positive 5th powers
1074 = number that is not the sum of two palindromes
1075 = number non-sum of two palindromes
1076 = number of strict trees weight 11{{Cite OEIS|A273873|Number of strict trees of weight n}}
1077 = number where 7 outnumbers every other digit in the number{{Cite OEIS|A292457|Numbers where 7 outnumbers any other digit}}
1078 = Euler transform of negative integers{{Cite OEIS|A073592|Euler transform of negative integers}}
1079 = every positive integer is the sum of at most 1079 tenth powers.
1080 = pentagonal number,{{Cite OEIS|A000326|Pentagonal numbers}} largely composite number{{Cite OEIS|A067128|Ramanujan's largely composite numbers}}
1081 = 46th triangular number, member of Padovan sequence{{Cite OEIS|A000931|Padovan sequence}}
1082 = central polygonal number
1083 = three-quarter square,{{Cite OEIS|A077043|2="Three-quarter squares": a(n) = n^2 - A002620(n)}} number of partitions of 53 into prime parts{{Cite OEIS|A000607|Number of partitions of n into prime parts}}
1084 = third spoke of a hexagonal spiral,{{Cite OEIS|A056107|Third spoke of a hexagonal spiral}} 1084⁶⁴ + 1 is prime
1085 = number of partitions of n into distinct parts > or = 2{{Cite OEIS|A025147|2=Number of partitions of n into distinct parts >= 2}}
1086 = Smith number,{{Cite OEIS|A006753|Smith numbers}} sum of totient function for first 59 integers
1087 = super-prime, cousin prime, lucky prime{{Cite OEIS|A031157|Numbers that are both lucky and prime}}
1088 = octo-triangular number, (triangular number result being 136){{Cite OEIS|A033996|2=8 times triangular numbers: a(n) = 4*n*(n+1)}} sum of two distinct powers of 2, (1024 + 64){{Cite OEIS|A018900|Sums of two distinct powers of 2}} number that is divisible by exactly seven primes with the inclusion of multiplicity{{Cite OEIS|A046308|Numbers that are divisible by exactly 7 primes counting multiplicity}}
1089 = 33², nonagonal number, centered octagonal number, first natural number whose digits in its decimal representation get reversed when multiplied by 9.{{Cite OEIS|A001232|2=Numbers n such that 9*n = (n written backwards)}}
1090 = sum of 5 positive 5th powers{{Cite OEIS|A003350|Numbers that are the sum of 5 positive 5th powers}}
1091 = cousin prime and twin prime with 1093
1092 = divisible by the number of primes below it
1093 = the smallest Wieferich prime (the only other known Wieferich prime is 3511Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 163), twin prime with 1091 and star number{{Cite OEIS|A003154|Centered 12-gonal numbers. Also star numbers}}
1094 = sum of 9 positive 5th powers, 1094⁶⁴ + 1 is prime
1095 = sum of 10 positive 5th powers,{{Cite OEIS|A003355|Numbers that are the sum of 10 positive 5th powers}} number that is not the sum of two palindromes
1096 = hendecagonal number,{{Cite OEIS|A051682|2=11-gonal (or hendecagonal) numbers: a(n) = n*(9*n-7)/2}} number of strict solid partitions of 18{{cite OEIS|A323657|Number of strict solid partitions of n}}
1097 = emirp, Chen prime
1098 = multiple of 9 containing digit 9 in its base-10 representation{{Cite OEIS|A121029|Multiples of 9 containing a 9 in their decimal representation}}
1099 = number where 9 outnumbers every other digit{{Cite OEIS|A292449|Numbers where 9 outnumbers any other digit}}

= 1100 to 1199 =

1100 = number of partitions of 61 into distinct squarefree parts{{cite OEIS|A087188|number of partitions of n into distinct squarefree parts}}
1101 = pinwheel number{{cite OEIS|A059993|Pinwheel numbers: 2*n^2 + 6*n + 1}}
1102 = sum of totient function for first 60 integers
1103 = Sophie Germain prime, balanced prime{{Cite OEIS|A006562|Balanced primes}}
1104 = Keith number{{Cite OEIS|A007629|Repfigit (REPetitive FIbonacci-like diGIT) numbers (or Keith numbers)}}
1105 = 33² + 4² = 32² + 9² = 31² + 12² = 23² + 24², Carmichael number,{{Cite web|url=https://oeis.org/A002997|title=Sloane's A002997 : Carmichael numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} magic constant of n × n normal magic square and n-queens problem for n = 13, decagonal number,{{Cite web|url=https://oeis.org/A001107|title=Sloane's A001107 : 10-gonal (or decagonal) numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} centered square number, Fermat pseudoprime{{cite OEIS|A001567|Fermat pseudoprimes to base 2, also called Sarrus numbers or Poulet numbers}}
1106 = number of regions into which the plane is divided when drawing 24 ellipses{{cite OEIS|A051890|2*(n^2 - n + 1)}}
1107 = number of non-isomorphic strict T₀ multiset partitions of weight 8{{cite OEIS|A319560|Number of non-isomorphic strict T_0 multiset partitions of weight n}}
1108 = number k such that k⁶⁴ + 1 is prime
1109 = Friedlander-Iwaniec prime,{{cite OEIS|A028916|Friedlander-Iwaniec primes: Primes of form a^2 + b^4}} Chen prime
1110 = k such that 2^k + 3 is prime{{cite OEIS|A057732|Numbers k such that 2^k + 3 is prime}}
1111 = 11 × 101, palindrome that is a product of two palindromic primes,{{cite OEIS|A046376|Palindromes with exactly 2 palindromic prime factors (counted with multiplicity), and no other prime factors}} repunit{{Cite web |title=A002275 - OEIS |url=https://oeis.org/search?q=A002275&language=english&go=Search |access-date=2024-03-08 |website=oeis.org}}
1112 = k such that 9^k - 2 is a prime{{cite OEIS|A128455|Numbers k such that 9^k - 2 is a prime}}
1113 = number of strict partions of 40{{cite OEIS|A000009|Expansion of Product_{m > 0} (1 + x^m); number of partitions of n into distinct parts; number of partitions of n into odd parts}}
1114 = number of ways to write 22 as an orderless product of orderless sums{{cite OEIS|A318949|Number of ways to write n as an orderless product of orderless sums}}
1115 = number of partitions of 27 into a prime number of parts{{cite OEIS|A038499|Number of partitions of n into a prime number of parts}}
1116 = divisible by the number of primes below it
1117 = number of diagonally symmetric polyominoes with 16 cells,{{cite OEIS|A006748|Number of diagonally symmetric polyominoes with n cells}} Chen prime
1118 = number of unimodular 2 × 2 matrices having all terms in {0,1,...,21}{{cite OEIS|A210000|Number of unimodular 2 X 2 matrices having all terms in {0,1,...,n}}}
1119 = number of bipartite graphs with 9 nodes{{cite OEIS|A033995|Number of bipartite graphs with n nodes}}
1120 = number k such that k⁶⁴ + 1 is prime
1121 = number of squares between 34² and 34⁴.{{cite OEIS|A028387|n + (n+1)^2}}
1122 = pronic number, divisible by the number of primes below it
1123 = balanced prime
1124 = Leyland number{{Cite OEIS|A076980|2=Leyland numbers: 3, together with numbers expressible as n^k + k^n nontrivially, i.e., n,k > 1 (to avoid n = (n-1)^1 + 1^(n-1))}} using 2 & 10 (2¹⁰ + 10²), spy number
1125 = Achilles number
1126 = number of 2 × 2 non-singular integer matrices with entries from {0, 1, 2, 3, 4, 5}{{cite OEIS|A062801|Number of 2 X 2 non-singular integer matrices with entries from {0,...,n}}}
1127 = maximal number of pieces that can be obtained by cutting an annulus with 46 cuts{{cite OEIS|A000096|n*(n+3)/2}}
1128 = 47th triangular number, 24th hexagonal number, divisible by the number of primes below it (188 × 6).{{Cite OEIS |A057809 |Numbers n such that pi(n) divides n. |access-date=2024-05-23 }} 1128 is the dimensional representation of the largest vertex operator algebra with central charge of 24, D₂₄.{{Cite journal |last1=Van Ekeren |first1=Jethro |last2=Lam |first2=Ching Hung |last3=Möller |first3=Sven |last4=Shimakura |first4=Hiroki |title=Schellekens' list and the very strange formula |url=https://www.sciencedirect.com/science/article/abs/pii/S0001870821000050 |journal=Advances in Mathematics |volume=380 |publisher=Elsevier |location=Amsterdam |year=2021 |pages=1–34 (107567) |doi=10.1016/j.aim.2021.107567 |mr=4200469 |zbl=1492.17027 |s2cid=218870375 |arxiv=2005.12248 }}
1129 = number of lattice points inside a circle of radius 19{{cite OEIS|A000328}}
1130 = skiponacci number{{cite OEIS|A001608|Perrin sequence}}
1131 = number of edges in the hexagonal triangle T(26){{cite OEIS|A140091|3*n*(n + 3)/2}}
1132 = number of simple unlabeled graphs with 9 nodes of 2 colors whose components are complete graphs{{cite OEIS|A005380}}
1133 = number of primitive subsequences of {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}{{cite OEIS|A051026|Number of primitive subsequences of 1, 2, ..., n}}
1134 = divisible by the number of primes below it, triangular matchstick number{{cite OEIS|A045943|Triangular matchstick numbers: 3*n*(n+1)/2|access-date=2022-06-02}}
1135 = centered triangular number{{cite OEIS|A005448|Centered triangular numbers: 3n(n-1)/2 + 1}}
1136 = number of [https://mathworld.wolfram.com/IndependentVertexSet.html independent vertex sets] and [https://mathworld.wolfram.com/VertexCover.html vertex covers] in the 7-[https://mathworld.wolfram.com/SunletGraph.html sunlet graph]{{cite OEIS|A080040|2*a(n-1) + 2*a(n-2) for n > 1}}
1137 = sum of values of vertices at level 5 of the hyperbolic Pascal pyramid{{cite OEIS|A264237|Sum of values of vertices at level n of the hyperbolic Pascal pyramid}}
1138 = recurring number in the works of George Lucas and his companies, beginning with his first feature film – THX 1138; particularly, a special code for Easter eggs on Star Wars DVDs.
1139 = wiener index of the windmill graph D(3,17){{cite OEIS|A033991|n*(4*n-1)}}
1140 = tetrahedral number{{Cite web|url=https://oeis.org/A000292|title=Sloane's A000292 : Tetrahedral numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1141 = 7-Knödel number{{cite OEIS|A208155|7-Knödel numbers}}
1142 = n such that n³² + 1 is prime,{{cite OEIS|A006315|Numbers n such that n^32 + 1 is prime}} spy number
1143 = number of set partitions of 8 elements with 2 connectors{{cite OEIS|A185982|Triangle read by rows: number of set partitions of n elements with k connectors}}
1144 is not the sum of a pair of twin primes{{cite OEIS|A007534|Even numbers that are not the sum of a pair of twin primes}}
1145 = 5-Knödel number{{cite OEIS|A050993|5-Knödel numbers}}
1146 is not the sum of a pair of twin primes
1147 = 31 × 37 (a product of 2 successive primes){{cite OEIS|A006094|Products of 2 successive primes}}
1148 is not the sum of a pair of twin primes
1149 = a product of two palindromic primes{{cite OEIS|A046368|Products of two palindromic primes}}
1150 = number of 11-iamonds without bilateral symmetry.{{Cite web|url=https://number.academy/1150|title=1150 (number)|website=The encyclopedia of numbers}}
1151 = first prime following a prime gap of 22,{{Cite web|url=https://oeis.org/A000101|title=Sloane's A000101 : Increasing gaps between primes (upper end)|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-07-10}} Chen prime
1152 = highly totient number,{{Cite web|url=https://oeis.org/A097942|title=Sloane's A097942 : Highly totient numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} 3-smooth number (2⁷×3²), area of a square with diagonal 48, Achilles number
1153 = super-prime, Proth prime{{Cite web|url=https://oeis.org/A080076|title=Sloane's A080076 : Proth primes|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1154 = 2 × 24² + 2 = number of points on surface of tetrahedron with edge length 24{{cite OEIS|

A005893|Number of points on surface of tetrahedron; coordination sequence for sodalite net (equals 2*n^2+2 for n > 0)}}

1155 = number of edges in the join of two cycle graphs, both of order 33,{{cite OEIS|n*(n+2)}} product of first four odd primes (3*5*7*11)
1156 = 34², octahedral number,{{Cite web|url=https://oeis.org/A005900|title=Sloane's A005900 : Octahedral numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} centered pentagonal number, centered hendecagonal number.{{Cite web|url=https://oeis.org/A069125|title=Sloane's A069125 : a(n) = (11*n^2 - 11*n + 2)/2|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1157 = smallest number that can be written as n^2+1 without any prime factors that can be written as a^2+1.{{Cite web|url=https://number.academy/1157|title=1157 (number)|website=The encyclopedia of numbers}}
1158 = number of points on surface of octahedron with edge length 17{{cite OEIS|A005899|Number of points on surface of octahedron}}
1159 = member of the Mian–Chowla sequence, a centered octahedral number{{cite OEIS|A001845|Centered octahedral numbers (crystal ball sequence for cubic lattice)|access-date=2022-06-02}}
1160 = octagonal number{{cite OEIS|A000567|Octagonal numbers: n*(3*n-2). Also called star numbers}}
1161 = sum of the first twenty-six primes
1162 = pentagonal number, sum of totient function for first 61 integers
1163 = smallest prime > 34².{{cite OEIS|A007491|Smallest prime > n^2}} See Legendre's conjecture. Chen prime.
1164 = number of chains of multisets that partition a normal multiset of weight 8, where a multiset is normal if it spans an initial interval of positive integers{{cite OEIS|A055887|Number of ordered partitions of partitions}}
1165 = 5-Knödel number
1166 = heptagonal pyramidal number{{cite OEIS|A002413|Heptagonal (or 7-gonal) pyramidal numbers}}
1167 = number of rational numbers which can be constructed from the set of integers between 1 and 43{{cite OEIS|A018805}}
1168 = antisigma(49){{cite OEIS|A024816|Antisigma(n): Sum of the numbers less than n that do not divide n}}
1169 = highly cototient number
1170 = highest possible score in a National Academic Quiz Tournaments (NAQT) match
1171 = super-prime
1172 = number of subsets of first 14 integers that have a sum divisible by 14{{Cite web|url=https://oeis.org/A063776|title=A063776 - OEIS|website=oeis.org}}
1173 = number of simple triangulation on a plane with 9 nodes{{Cite web|url=https://oeis.org/A000256|title=A000256 - OEIS|website=oeis.org}}
1174 = number of widely totally strongly normal compositions of 16
1175 = maximal number of pieces that can be obtained by cutting an annulus with 47 cuts
1176 = 48th triangular number
1177 = heptagonal number
1178 = number of surface points on a cube with edge-length 15
1179 = number of different permanents of binary 7*7 matrices{{Cite web|url=https://number.academy/1179|title=1179 (number)|website=The encyclopedia of numbers}}
1180 = smallest number of non-integral partitions into non-integral power >1000.{{Cite web|url=https://oeis.org/A000339|title=A000339 - OEIS|website=oeis.org}}
1181 = smallest k over 1000 such that 8*10^k-49 is prime.{{Cite web|url=https://oeis.org/A271269|title=A271269 - OEIS|website=oeis.org}}
1182 = number of necklaces possible with 14 beads of 2 colors (that cannot be turned over){{Cite web|url=https://oeis.org/A000031|title=A000031 - OEIS|website=oeis.org}}
1183 = pentagonal pyramidal number
1184 = amicable number with 1210{{cite book |title=Number Story: From Counting to Cryptography |url=https://archive.org/details/numberstoryfromc00higg_612 |url-access=limited |last=Higgins |first=Peter |year=2008 |publisher=Copernicus |location=New York |isbn=978-1-84800-000-1 |page=[https://archive.org/details/numberstoryfromc00higg_612/page/n69 61] }}
1185 = number of partitions of 45 into pairwise relatively prime parts{{cite OEIS|A051424|Number of partitions of n into pairwise relatively prime parts}}
1186 = number of diagonally symmetric polyominoes with 15 cells, number of partitions of 54 into prime parts
1187 = safe prime, Stern prime,{{Cite web|url=https://oeis.org/A042978|title=Sloane's A042978 : Stern primes|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} balanced prime, Chen prime
1188 = first 4 digit multiple of 18 to contain 18{{Cite web|url=https://oeis.org/A121038|title=A121038 - OEIS|website=oeis.org}}
1189 = number of squares between 35² and 35⁴.
1190 = pronic number, number of cards to build a 28-tier house of cards{{cite OEIS|A005449|Second pentagonal numbers: n*(3*n + 1)/2}}
1191 = 35² - 35 + 1 = H₃₅ (the 35th Hogben number){{cite OEIS|A002061|Central polygonal numbers: n^2 - n + 1}}
1192 = sum of totient function for first 62 integers
1193 = a number such that 4¹¹⁹³ - 3¹¹⁹³ is prime, Chen prime
1194 = number of permutations that can be reached with 8 moves of 2 bishops and 1 rook on a 3 × 3 chessboard{{Cite web|url=https://oeis.org/A175654|title=A175654 - OEIS|website=oeis.org}}
1195 = smallest four-digit number for which a⁻¹(n) is an integer is a(n) is 2*a(n-1) - (-1)ⁿoeis.org/A062092
1196 = $\sum_{k=1}^{38} \sigma(k)$ {{cite OEIS|A024916|Sum_1^n sigma(k)}}
1197 = pinwheel number
1198 = centered heptagonal number
1199 = area of the 20th [https://oeis.org/A080663/a080663.jpg conjoined trapezoid]>{{cite OEIS|A080663|3*n^2 - 1}}

= 1200 to 1299 =

1200 = the long thousand, ten "long hundreds" of 120 each, the traditional reckoning of large numbers in Germanic languages, the number of households the Nielsen ratings sample,Meehan, Eileen R., Why TV is not our fault: television programming, viewers, and who's really in control Lanham, MD: Rowman & Littlefield, 2005 number k such that k⁶⁴ + 1 is prime
1201 = centered square number, super-prime, centered decagonal number
1202 = [https://mathworld.wolfram.com/PlaneDivisionbyEllipses.html number of regions] the plane is divided into by 25 ellipses
1203: first 4 digit number in the coordinating sequence for the (2,6,∞) tiling of the hyperbolic plane{{Cite web|url=https://oeis.org/A265070|title=A265070 - OEIS|website=oeis.org}}
1204: magic constant of a 7 × 7 × 7 magic cube{{Cite web|url=https://number.academy/1204|title=1204 (number)|website=The encyclopedia of numbers}}
1205 = number of partitions of 28 such that the number of odd parts is a part{{cite OEIS|A240574|Number of partitions of n such that the number of odd parts is a part}}
1206 = 29-gonal number {{Cite web|url=https://oeis.org/A303815|title=A303815 - OEIS|website=oeis.org}}
1207 = composite de Polignac number{{cite OEIS|A098237|Composite de Polignac numbers}}
1208 = number of strict chains of divisors starting with the superprimorial A006939(3){{cite OEIS|A337070|Number of strict chains of divisors starting with the superprimorial A006939(n)}}
1209 = The product of all ordered non-empty subsets of {3,1} if {a,b} is a||b: 1209=1*3*13*31
1210 = amicable number with 1184Higgins, ibid.
1211 = composite de Polignac number
1212 = $\sum_{k=0}^{17} p(k)$ , where $p$ is the number of partions of $k$ {{cite OEIS|A000070|Sum_{0..n} A000041(k)}}
1213 = emirp
1214 = sum of first 39 composite numbers,{{cite OEIS|A053767|Sum of first n composite numbers}} spy number
1215 = number of edges in the hexagonal triangle T(27)
1216 = nonagonal number{{Cite web|url=https://oeis.org/A001106|title=Sloane's A001106 : 9-gonal (or enneagonal or nonagonal) numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1217 = super-prime, Proth prime
1218 = triangular matchstick number
1219 = Mertens function zero, centered triangular number
1220 = Mertens function zero, number of binary vectors of length 16 containing no singletons{{cite OEIS|A006355|Number of binary vectors of length n containing no singletons}}
1221 = product of the first two digit, and three digit repdigit
1222 = hexagonal pyramidal number
1223 = Sophie Germain prime, balanced prime, 200th prime number
1224 = number of edges in the join of two cycle graphs, both of order 34
1225 = 35², 49th triangular number, 2nd nontrivial square triangular number,{{Cite web|url=https://oeis.org/A001110|title=Sloane's A001110 : Square triangular numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} 25th hexagonal number, and the smallest number >1 to be all three.{{Cite web |title=A046177 - OEIS |url=https://oeis.org/A046177 |access-date=2024-12-18 |website=oeis.org}} Additionally a centered octagonal number,{{Cite web|url=https://oeis.org/A016754|title=Sloane's A016754 : Odd squares: a(n) = (2n+1)^2. Also centered octagonal numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} icosienneagonal,{{cite OEIS|A303815|Generalized 29-gonal (or icosienneagonal) numbers}} hexacontagonal,{{cite OEIS|A249911|60-gonal (hexacontagonal) numbers}} and hecatonicositetragonal (124-gonal) number, and the sum of 5 consecutive odd cubes (1³ + 3³ + 5³ + 7³ + 9³)
1226 = number of rooted identity trees with 15 nodes {{Cite web|url=https://oeis.org/A004111|title=A004111 - OEIS|website=oeis.org}}
1227 = smallest number representable as the sum of 3 triangular numbers in 27 ways{{Cite web|url=https://oeis.org/A061262|title=A061262 - OEIS|website=oeis.org}}
1228 = sum of totient function for first 63 integers
1229 = Sophie Germain prime, number of primes under 10,000, emirp
1230 = the Mahonian number: T(9, 6){{cite OEIS|A008302|Triangle of Mahonian numbers T(n,k): coefficients in expansion of Product{0..n-1} (1 + x + ... + x^i), where k ranges from 0 to A000217(n-1). Also enumerates permutations by their major index}}
1231 = smallest mountain emirp, as 121, smallest mountain number is 11 × 11
1232 = number of labeled ordered set of partitions of a 7-set into odd parts{{Cite web|url=https://oeis.org/A006154|title=A006154 - OEIS|website=oeis.org}}
1233 = 12² + 33²
1234 = number of parts in all partitions of 30 into distinct parts, smallest whole number containing all numbers from 1 to 4
1235 = excluding duplicates, contains the first four Fibonacci numbers {{Cite web|url=https://oeis.org/A000045|title=A000045 - OEIS|website=oeis.org}}
1236 = 617 + 619: sum of twin prime pair{{cite OEIS|A054735|Sums of twin prime pairs}}
1237 = prime of the form 2p-1
1238 = number of partitions of 31 that do not contain 1 as a part
1239 = toothpick number in 3D{{Cite web|url=https://oeis.org/A160160|title=A160160 - OEIS|website=oeis.org}}
1240 = square pyramidal number
1241 = centered cube number,{{Cite web|url=https://oeis.org/A005898|title=Sloane's A005898 : Centered cube numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} spy number
1242 = decagonal number
1243 = composite de Polignac number
1244 = number of complete partitions of 25{{cite OEIS|A126796|Number of complete partitions of n}}
1245 = Number of labeled spanning intersecting set-systems on 5 vertices.oeis.org/A305843
1246 = number of partitions of 38 such that no part occurs more than once{{Cite web|url=https://oeis.org/A007690|title=A007690 - OEIS|website=oeis.org}}
1247 = pentagonal number
1248 = the first four powers of 2 concatenated together
1249 = emirp, trimorphic number{{Cite web|url=https://oeis.org/A033819|title=Sloane's A033819 : Trimorphic numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1250 = area of a square with diagonal 50
1251 = 2 × 25² + 1 = number of different 2 × 2 determinants with integer entries from 0 to 25{{cite OEIS|A058331|2*n^2 + 1}}
1252 = 2 × 25² + 2 = number of points on surface of tetrahedron with edgelength 25
1253 = number of partitions of 23 with at least one distinct part{{cite OEIS|A144300|Number of partitions of n minus number of divisors of n}}
1254 = number of partitions of 23 into relatively prime parts{{cite OEIS|A000837|Number of partitions of n into relatively prime parts. Also aperiodic partitions.}}
1255 = Mertens function zero, number of ways to write 23 as an orderless product of orderless sums, number of partitions of 23{{cite OEIS|A000041|a(n) is the number of partitions of n (the partition numbers)}}
1256 = 1 × 2 × (5²)² + 6,{{cite OEIS|A193757|Numbers which can be written with their digits in order and using only a plus and a squaring operator}} Mertens function zero
1257 = number of lattice points inside a circle of radius 20
1258 = 1 × 2 × (5²)² + 8, Mertens function zero
1259 = highly cototient number
1260 = the 16th highly composite number,{{Cite web|url=https://oeis.org/A002182|title=Sloane's A002182 : Highly composite numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} pronic number, the smallest vampire number,{{Cite web|url=https://oeis.org/A014575|title=Sloane's A014575 : Vampire numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} sum of totient function for first 64 integers, number of strict partions of 41 and appears twice in the Book of Revelation
1261 = star number, Mertens function zero
1262 = maximal number of regions the plane is divided into by drawing 36 circles{{cite OEIS|A014206|n^2 + n + 2}}
1263 = rounded total surface area of a regular tetrahedron with edge length 27{{cite OEIS|A070169|Rounded total surface area of a regular tetrahedron with edge length n}}
1264 = sum of the first 27 primes
1265 = number of rooted trees with 43 vertices in which vertices at the same level have the same degree{{cite OEIS|A003238|Number of rooted trees with n vertices in which vertices at the same level have the same degree}}
1266 = centered pentagonal number, Mertens function zero
1267 = 7-Knödel number
1268 = number of partitions of 37 into prime power parts{{cite OEIS|A023894|Number of partitions of n into prime power parts}}
1269 = least number of triangles of the Spiral of Theodorus to complete 11 revolutions{{cite OEIS|A072895|Least k for the Theodorus spiral to complete n revolutions}}
1270 = 25 + 24×26 + 23×27,{{cite OEIS|A100040|2*n^2 + n - 5}} Mertens function zero
1271 = sum of first 40 composite numbers
1272 = sum of first 41 nonprimes{{cite OEIS|A051349|Sum of first n nonprimes}}
1273 = 19 × 67 = 19 × prime(19){{cite OEIS|A033286|n * prime(n)}}
1274 = sum of the nontriangular numbers between successive triangular numbers
1275 = 50th triangular number, equivalently the sum of the first 50 natural numbers
1276 = number of irredundant sets in the 25-cocktail party graph{{cite OEIS|A084849|1 + n + 2*n^2}}
1277 = the start of a prime constellation of length 9 (a "prime nonuple")
1278 = number of Narayana's cows and calves after 20 years{{cite OEIS|A000930|Narayana's cows sequence}}
1279 = Mertens function zero, Mersenne prime exponent
1280 = Mertens function zero, number of parts in all compositions of 9{{cite OEIS|A001792|(n+2)*2^(n-1)}}
1281 = octagonal number
1282 = Mertens function zero, number of partitions of 46 into pairwise relatively prime parts
1283 = safe prime
1284 = 641 + 643: sum of twin prime pair
1285 = Mertens function zero, number of free nonominoes, number of parallelogram polyominoes with 10 cells.{{cite OEIS|A006958|Number of parallelogram polyominoes with n cells (also called staircase polyominoes, although that term is overused)}}
1286 = number of inequivalent connected planar figures that can be formed from five 1 X 2 rectangles (or dominoes) such that each pair of touching rectangles shares exactly one edge, of length 1, and the adjacency graph of the rectangles is a tree{{cite OEIS|A216492|Number of inequivalent connected planar figures that can be formed from n 1 X 2 rectangles (or dominoes) such that each pair of touching rectangles shares exactly one edge, of length 1, and the adjacency graph of the rectangles is a tree}}
1287 = ${13 \choose 5}$ {{cite OEIS|A007318|Pascal's triangle read by rows}}
1288 = heptagonal number
1289 = Sophie Germain prime, Mertens function zero
1290 = $\frac{1289 + 1291}{2}$ , average of a twin prime pair{{cite OEIS|A014574|Average of twin prime pairs}}
1291 = largest prime < 6⁴,{{cite OEIS|A173831|Largest prime < n^4}} Mertens function zero
1292 = number such that phi(1292) = phi(sigma(1292)),{{cite OEIS|A006872|Numbers k such that phi(k) equals phi(sigma(k))}} Mertens function zero
1293 = $\sum_{j=1}^n j \times prime(j)$ {{cite OEIS|A014285|Sum_{1..n} j*prime(j)}}
1294 = rounded volume of a regular octahedron with edge length 14{{cite OEIS|A071400|Rounded volume of a regular octahedron with edge length n}}
1295 = number of edges in the join of two cycle graphs, both of order 35
1296 = 36² = 6⁴, sum of the cubes of the first eight positive integers, the number of rectangles on a normal 8 × 8 chessboard, also the maximum font size allowed in Adobe InDesign, number of combinations of 2 characters(00-ZZ)
1297 = super-prime, Mertens function zero, pinwheel number
1298 = number of partitions of 55 into prime parts
1299 = Mertens function zero, number of partitions of 52 such that the smallest part is greater than or equal to number of parts{{cite OEIS|A003114|Number of partitions of n into parts 5k+1 or 5k+4}}

= 1300 to 1399 =

1300 = Sum of the first 4 fifth powers, Mertens function zero, largest possible win margin in an NAQT match; smallest even odd-factor hyperperfect number
1301 = centered square number, Honaker prime,{{cite OEIS|A033548|Honaker primes: primes P(k) such that sum of digits of P(k) equals sum of digits of k}} number of trees with 13 unlabeled nodes{{cite OEIS|A000055|Number of trees with n unlabeled nodes}}
1302 = Mertens function zero, number of edges in the hexagonal triangle T(28)
1303 = prime of form 21n+1 and 31n+1{{Cite web|url=https://oeis.org/A124826|title=A124826 - OEIS|website=oeis.org}}{{Cite web|url=https://oeis.org/A142005|title=A142005 - OEIS|website=oeis.org}}
1304 = sum of 1304₆ and 1304 ₉ which is 328+976
1305 = triangular matchstick number
1306 = Mertens function zero. In base 10, raising the digits of 1306 to powers of successive integers equals itself: {{nowrap|1=1306 = 1¹ + 3² + 0³ + 6⁴.}} 135, 175, 518, and 598 also have this property. Centered triangular number.
1307 = safe prime
1308 = sum of totient function for first 65 integers
1309 = the first sphenic number followed by two consecutive such number
1310 = smallest number in the middle of a set of three sphenic numbers
1311 = number of integer partitions of 32 with no part dividing all the others{{cite OEIS|A338470|Number of integer partitions of n with no part dividing all the others}}
1312 = member of the Mian-Chowla sequence;
1313 = sum of all parts of all partitions of 14 {{Cite web|url=https://oeis.org/A066186|title=A066186 - OEIS|website=oeis.org}}
1314 = number of integer partitions of 41 whose distinct parts are connected{{cite OEIS|A304716|Number of integer partitions of n whose distinct parts are connected}}
1315 = 10^(2n+1)-7*10^n-1 is prime.{{Cite web|url=https://oeis.org/A115073|title=A115073 - OEIS|website=oeis.org}}
1316 = Euler transformation of sigma(11){{Cite web|url=https://oeis.org/A061256|title=A061256 - OEIS|website=oeis.org}}
1317 = 1317 Only odd four digit number to divide the concatenation of all number up to itself in base 25{{Cite web|url=https://oeis.org/A061954|title=A061954 - OEIS|website=oeis.org}}
1318⁵¹² + 1 is prime,{{cite OEIS|A057465|Numbers k such that k^512 + 1 is prime}} Mertens function zero
1319 = safe prime
1320 = 659 + 661: sum of twin prime pair
1321 = Friedlander-Iwaniec prime
1322 = area of the 21st [https://oeis.org/A080663/a080663.jpg conjoined trapezoid]
1323 = Achilles number
1324 = if D(n) is the nth representation of 1, 2 arranged lexicographically. 1324 is the first non-1 number which is D(D(x)){{Cite web|url=https://oeis.org/A030299|title=A030299 - OEIS|website=oeis.org}}
1325 = Markov number,{{Cite web|url=https://oeis.org/A002559|title=Sloane's A002559 : Markoff (or Markov) numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} centered tetrahedral number{{cite OEIS|A005894|Centered tetrahedral numbers}}
1326 = 51st triangular number, hexagonal number, Mertens function zero
1327 = first prime followed by 33 consecutive composite numbers
1328 = sum of totient function for first 66 integers
1329 = Mertens function zero, sum of first 41 composite numbers
1330 = tetrahedral number, forms a Ruth–Aaron pair with 1331 under second definition
1331 = 11³, centered heptagonal number, forms a Ruth–Aaron pair with 1330 under second definition. This is the only non-trivial cube of the form x² + x − 1, for x = 36.
1332 = pronic number
1333 = 37² - 37 + 1 = H₃₇ (the 37th Hogben number)
1334 = maximal number of regions the plane is divided into by drawing 37 circles
1335 = pentagonal number, Mertens function zero
1336 = sum of gcd(x, y) for 1 <= x, y <= 24,{{cite OEIS|A018806|Sum of gcd(x, y)}} Mertens function zero
1337 = Used in the novel form of spelling called leet. Approximate melting point of gold in kelvins.
1338 = atomic number of the noble element of period 18,{{cite OEIS|A018227|Magic numbers: atoms with full shells containing any of these numbers of electrons are considered electronically stable}} Mertens function zero
1339 = First 4 digit number to appear twice in the sequence of sum of cubes of primes dividing n{{Cite web|url=https://oeis.org/A005064|title=A005064 - OEIS|website=oeis.org}}
1340 = k such that 5 × 2^k - 1 is prime{{cite OEIS|A001770|Numbers k such that 5*2^k - 1 is prime}}
1341 = First mountain number with 2 jumps of more than one.
1342 = $\sum_{k=1}^{40} \sigma(k)$ , Mertens function zero
1343 = [https://oeis.org/A144391/a144391.jpg cropped hexagone]{{cite OEIS|A144391|3*n^2 + n - 1}}
1344 = 37² - 5², the only way to express 1344 as a difference of prime squares{{cite OEIS|A090781|Numbers that can be expressed as the difference of the squares of primes in just one distinct way}}
1345 = k such that k, k+1 and k+2 are products of two primes{{cite OEIS|A056809|Numbers k such that k, k+1 and k+2 are products of two primes}}
1346 = number of locally disjointed rooted trees with 10 nodes{{Cite web|url=https://oeis.org/A316473|title=A316473 - OEIS|website=oeis.org}}
1347 = concatenation of first 4 Lucas numbers {{Cite web|url=https://oeis.org/A000032|title=A000032 - OEIS|website=oeis.org}}
1348 = number of ways to stack 22 pennies such that every penny is in a stack of one or two{{Cite web|url=https://number.academy/1348|title=1348 (number)|website=The encyclopedia of numbers}}
1349 = Stern-Jacobsthal number{{cite OEIS|A101624|Stern-Jacobsthal number}}
1350 = nonagonal number
1351 = number of partitions of 28 into a prime number of parts
1352 = number of surface points on a cube with edge-length 16, Achilles number
1353 = 2 × 26² + 1 = number of different 2 × 2 determinants with integer entries from 0 to 26
1354 = 2 × 26² + 2 = number of points on surface of tetrahedron with edgelength 26
1355 appears for the first time in the Recamán's sequence at n = 325,374,625,245.{{cite OEIS|A064228|From Recamán's sequence (A005132): values of n achieving records in A057167}} Or in other words A057167(1355) = 325,374,625,245{{cite OEIS|A057167|Term in Recamán's sequence A005132 where n appears for first time, or -1 if n never appears}}{{cite OEIS|A064227|From Recamán's sequence (A005132): record values in A057167}}
1356 is not the sum of a pair of twin primes
1357 = number of nonnegative solutions to x² + y² ≤ 41²{{cite OEIS|A000603}}
1358 = rounded total surface area of a regular tetrahedron with edge length 28
1359 is the 42d term of Flavius Josephus's sieve{{cite OEIS|A000960|Flavius Josephus's sieve: Start with the natural numbers; at the k-th sieving step, remove every (k+1)-st term of the sequence remaining after the (k-1)-st sieving step; iterate}}
1360 = 37² - 3², the only way to express 1360 as a difference of prime squares
1361 = first prime following a prime gap of 34, centered decagonal number, 3rd Mills' prime, Honaker prime
1362 = number of achiral integer partitions of 48{{cite OEIS|A330224|Number of achiral integer partitions of n}}
1363 = the number of ways to modify a circular arrangement of 14 objects by swapping one or more adjacent pairs{{cite OEIS|A001610|a(n-1) + a(n-2) + 1}}
1364 = Lucas number{{cite OEIS|A000032|Lucas numbers: L(n-1) + L(n-2)}}
1365 = pentatope number{{Cite web|url=https://oeis.org/A000332|title=Sloane's A000332 : Binomial coefficient binomial(n,4) = n*(n-1)*(n-2)*(n-3)/24|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1366 = Arima number, after Yoriyuki Arima who in 1769 constructed this sequence as the number of moves of the outer ring in the optimal solution for the Chinese Rings puzzle{{cite OEIS|A005578|Arima sequence}}
1367 = safe prime, balanced prime, sum of three, nine, and eleven consecutive primes (449 + 457 + 461, 131 + 137 + 139 + 149 + 151 + 157 + 163 + 167 + 173, and 101 + 103 + 107 + 109 + 113 + 127 + 131 + 137 + 139 + 149 + 151),
1368 = number of edges in the join of two cycle graphs, both of order 36
1369 = 37², centered octagonal number
1370 = σ₂(37): sum of squares of divisors of 37{{cite OEIS|A001157|sigma_2(n): sum of squares of divisors of n}}
1371 = sum of the first 28 primes
1372 = Achilles number
1373 = number of lattice points inside a circle of radius 21
1374 = number of unimodular 2 × 2 matrices having all terms in {0,1,...,23}
1375 = decagonal pyramidal number
1376 = primitive abundant number (abundant number all of whose proper divisors are deficient numbers){{cite OEIS|A071395|Primitive abundant numbers (abundant numbers all of whose proper divisors are deficient numbers)}}
1377 = maximal number of pieces that can be obtained by cutting an annulus with 51 cuts
1378 = 52nd triangular number
1379 = magic constant of n × n normal magic square and n-queens problem for n = 14.
1380 = number of 8-step mappings with 4 inputs{{cite OEIS|A005945|Number of n-step mappings with 4 inputs}}
1381 = centered pentagonal number Mertens function zero
1382 = first 4 digit tetrachi number {{Cite web|url=https://oeis.org/A001631|title=A001631 - OEIS|website=oeis.org|accessdate=25 June 2023}}
1383 = 3 × 461. 10¹³⁸³ + 7 is prime{{cite OEIS|A088274|Numbers k such that 10^k + 7 is prime}}
1384 = $\sum_{k=1}^{41} \sigma(k)$
1385 = up/down number{{cite OEIS|A000111|Euler or up/down numbers: e.g.f. sec(x) + tan(x)}}
1386 = octagonal pyramidal number{{cite OEIS|A002414|Octagonal pyramidal numbers}}
1387 = 5th Fermat pseudoprime of base 2,{{Cite web|url=https://oeis.org/A001567|title=Sloane's A001567 : Fermat pseudoprimes to base 2|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} 22nd centered hexagonal number and the 19th decagonal number, second Super-Poulet number.{{Cite web|url=https://oeis.org/A050217|title=Sloane's A050217 : Super-Poulet numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1388 = 4 × 19² - 3 × 19 + 1 and is therefore on the x-axis of Ulams spiral{{cite OEIS|A054552|4*n^2 - 3*n + 1}}
1389 = sum of first 42 composite numbers
1390 = sum of first 43 nonprimes
1391 = number of rational numbers which can be constructed from the set of integers between 1 and 47
1392 = number of edges in the hexagonal triangle T(29)
1393 = 7-Knödel number
1394 = sum of totient function for first 67 integers
1395 = vampire number, member of the Mian–Chowla sequence triangular matchstick number
1396 = centered triangular number
1397 = $\left \lfloor 5^{\frac{9}{2}} \right \rfloor$ {{cite OEIS|A017919|Powers of sqrt(5) rounded down}}
1398 = number of integer partitions of 40 whose distinct parts are connected
1399 = emirp{{cite OEIS|A109308|Lesser emirps (primes whose digit reversal is a larger prime)}}

= 1400 to 1499 =

1400 = number of sum-free subsets of {1, ..., 15}{{cite OEIS|A007865|Number of sum-free subsets of {1, ..., n}}}
1401 = pinwheel number
1402 = number of integer partitions of 48 whose augmented differences are distinct,{{cite OEIS|A325349|Number of integer partitions of n whose augmented differences are distinct}} number of signed trees with 8 nodes{{cite OEIS|A000060|Number of signed trees with n nodes}}
1403 = smallest x such that M(x) = 11, where M() is Mertens function{{cite OEIS|A051400|Smallest value of x such that M(x) equals n, where M() is Mertens's function A002321}}
1404 = heptagonal number
1405 = 26² + 27², 7² + 8² + ... + 16², centered square number
1406 = pronic number, semi-meandric number{{Cite web|url=https://oeis.org/A000682|title=Sloane's A000682 : Semimeanders|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1407 = 38² - 38 + 1 = H₃₈ (the 38th Hogben number)
1408 = maximal number of regions the plane is divided into by drawing 38 circles
1409 = super-prime, Sophie Germain prime, smallest number whose eighth power is the sum of 8 eighth powers, Proth prime
1410 = denominator of the 46th Bernoulli number{{cite OEIS|A002445|Denominators of Bernoulli numbers B_{2n}}}
1411 = LS(41){{cite OEIS|A045918|Describe n. Also called the "Say What You See" or "Look and Say" sequence LS(n)}}
1412 = LS(42), spy number
1413 = LS(43)
1414 = smallest composite that when added to sum of prime factors reaches a prime after 27 iterations{{cite OEIS|A050710|Smallest composite that when added to sum of prime factors reaches a prime after n iterations}}
1415 = the Mahonian number: T(8, 8)
1416 = LS(46)
1417 = number of partitions of 32 in which the number of parts divides 32{{cite OEIS|A067538|Number of partitions of n in which the number of parts divides n}}
1418 = smallest x such that M(x) = 13, where M() is Mertens function
1419 = Zeisel number{{Cite web|url=https://oeis.org/A051015|title=Sloane's A051015 : Zeisel numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1420 = Number of partitions of 56 into prime parts
1421 = maximum dimension of Euclidean spaces which suffice for every smooth compact Riemannian 29-manifold to be realizable as a sub-manifold,{{cite OEIS|A059845|n*(3*n + 11)/2}} spy number
1422 = number of partitions of 15 with two parts marked{{cite OEIS|A000097|Number of partitions of n if there are two kinds of 1's and two kinds of 2's}}
1423 = 200 + 1223 and the 200th prime is 1223{{cite OEIS|A061068|Primes which are the sum of a prime and its subscript}} Also Used as a Hate symbol
1424 = number of nonnegative solutions to x² + y² ≤ 42²
1425 = self-descriptive number in base 5
1426 = sum of totient function for first 68 integers, pentagonal number, number of strict partions of 42
1427 = twin prime together with 1429{{cite OEIS|A001359|Lesser of twin primes}}
1428 = number of complete ternary trees with 6 internal nodes, or 18 edges{{cite OEIS|A001764|binomial(3*n,n)/(2*n+1) (enumerates ternary trees and also noncrossing trees)}}
1429 = number of partitions of 53 such that the smallest part is greater than or equal to number of parts
1430 = Catalan number{{Cite web|url=https://oeis.org/A000108|title=Sloane's A000108 : Catalan numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1431 = 53rd triangular number, hexagonal number
1432 = member of Padovan sequence
1433 = super-prime, Honaker prime, typical port used for remote connections to Microsoft SQL Server databases
1434 = rounded volume of a regular tetrahedron with edge length 23{{cite OEIS|A071399|Rounded volume of a regular tetrahedron with edge length n}}
1435 = vampire number; the standard railway gauge in millimetres, equivalent to {{convert|4|ft|8+1/2|in}}
1436 = discriminant of a totally real cubic field{{cite OEIS|A006832|Discriminants of totally real cubic fields}}
1437 = smallest number of complexity 20: smallest number requiring 20 1's to build using +, * and ^{{cite OEIS|A003037|Smallest number of complexity n: smallest number requiring n 1's to build using +, * and ^}}
1438 = k such that 5 × 2^k - 1 is prime
1439 = Sophie Germain prime, safe prime
1440 = a highly totient number, a largely composite number and a 481-gonal number. Also, the number of minutes in one day, the blocksize of a standard {{sfrac|3|1|2}} floppy disk, and the horizontal resolution of WXGA(II) computer displays
1441 = star number
1442 = number of parts in all partitions of 31 into distinct parts
1443 = the sum of the second trio of three-digit permutable primes in decimal: 337, 373, and 733. Also the number of edges in the join of two cycle graphs, both of order 37
1444 = 38², smallest pandigital number in Roman numerals
1445 = $\sum_{k=0}^3 \left( \binom{3}{k} \times \binom{3+k}{k} \right) ^2$ {{cite OEIS|A005259|Apery (Apéry) numbers: Sum_0^n (binomial(n,k)*binomial(n+k,k))^2}}
1446 = number of points on surface of octahedron with edge length 19
1447 = super-prime, happy number
1448 = number k such that phi(prime(k)) is a square{{cite OEIS|A062325|Numbers k for which phi(prime(k)) is a square}}
1449 = Stella octangula number
1450 = σ₂(34): sum of squares of divisors of 34
1451 = Sophie Germain prime
1452 = first Zagreb index of the complete graph K₁₂{{cite OEIS|A011379|n^2*(n+1)}}
1453 = Sexy prime with 1459
1454 = 3 × 22² + 2 = number of points on surface of square pyramid of side-length 22{{cite OEIS|A005918|Number of points on surface of square pyramid: 3*n^2 + 2 (n>0)}}
1455 = k such that geometric mean of phi(k) and sigma(k) is an integer{{cite OEIS|A011257|Geometric mean of phi(n) and sigma(n) is an integer}}
1456 = number of regions in regular 15-gon with all diagonals drawn{{cite OEIS|A007678|Number of regions in regular n-gon with all diagonals drawn}}
1457 = 2 × 27² − 1 = a [https://oeis.org/A056220/a056220.jpg twin square]{{cite OEIS|A056220|2*n^2 - 1}}
1458 = maximum determinant of an 11 by 11 matrix of zeroes and ones, 3-smooth number (2×3⁶)
1459 = Sexy prime with 1453, sum of nine consecutive primes (139 + 149 + 151 + 157 + 163 + 167 + 173 + 179 + 181), Pierpont prime
1460 = The number of years that would have to pass in the Julian calendar in order to accrue a full year's worth of leap days.
1461 = number of partitions of 38 into prime power parts
1462 = (35 - 1) × (35 + 8) = the first Zagreb index of the wheel graph with 35 vertices{{cite OEIS|A028569|n*(n + 9)}}
1463 = total number of parts in all partitions of 16
1464 = rounded total surface area of a regular icosahedron with edge length 13{{cite OEIS|A071398|Rounded total surface area of a regular icosahedron with edge length n}}
1465 = 5-Knödel number
1466 = $\sum_{k=1}^{256} d(k)$ , where $d(k)$ = number of divisors of $k$ {{cite OEIS|A085831|Sum_1^{2^n} d(k) where d(k) is the number of divisors of k (A000005)}}
1467 = number of partitions of 39 with zero crank{{cite OEIS|A064410|Number of partitions of n with zero crank}}
1468 = number of polyhexes with 11 cells that tile the plane by translation{{cite OEIS|A075207|Number of polyhexes with n cells that tile the plane by translation}}
1469 = octahedral number, highly cototient number
1470 = pentagonal pyramidal number,{{Cite web|url=https://oeis.org/A002411|title=Sloane's A002411 : Pentagonal pyramidal numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} sum of totient function for first 69 integers
1471 = super-prime, centered heptagonal number
1472 = number of overpartitions of 15{{cite OEIS|A015128|Number of overpartitions of n: an overpartition of n is an ordered sequence of nonincreasing integers that sum to n, where the first occurrence of each integer may be overlined}}
1473 = [https://oeis.org/A144391/a144391.jpg cropped hexagone]
1474 = $\frac{44(44 + 1)}{2} + \frac{44^2}{4}$ : triangular number plus quarter square (i.e., A000217(44) + A002620(44)){{cite OEIS|A006578|Triangular numbers plus quarter squares: n*(n+1)/2 + floor(n^2/4) (i.e., A000217(n) + A002620(n))}}
1475 = number of partitions of 33 into parts each of which is used a different number of times{{cite OEIS|A098859|Number of partitions of n into parts each of which is used a different number of times}}
1476 = coreful perfect number{{cite OEIS|A307958|Coreful perfect numbers}}
1477 = 7-Knödel number
1478 = total number of largest parts in all compositions of 11{{cite OEIS|A097979|Total number of largest parts in all compositions of n}}
1479 = number of planar partitions of 12{{cite OEIS|A000219|Number of planar partitions (or plane partitions) of n}}
1480 = sum of the first 29 primes
1481 = Sophie Germain prime
1482 = pronic number, number of unimodal compositions of 15 where the maximal part appears once{{cite OEIS|A006330|Number of corners, or planar partitions of n with only one row and one column}}
1483 = 39² - 39 + 1 = H₃₉ (the 39th Hogben number)
1484 = maximal number of regions the plane is divided into by drawing 39 circles
1485 = 54th triangular number
1486 = number of strict solid partitions of 19
1487 = safe prime
1488 = triangular matchstick number
1489 = centered triangular number
1490 = tetranacci number{{Cite web|url=https://oeis.org/A000078|title=Sloane's A000078 : Tetranacci numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1491 = nonagonal number, Mertens function zero
1492 = discriminant of a totally real cubic field, Mertens function zero
1493 = Stern prime
1494 = sum of totient function for first 70 integers
1495 = 9###{{cite OEIS|A114411|Triple primorial n###}}
1496 = square pyramidal number
1497 = skiponacci number
1498 = number of flat partitions of 41{{cite OEIS|A034296|Number of flat partitions of n}}
1499 = Sophie Germain prime, super-prime

= 1500 to 1599 =

1500 = hypotenuse in three different Pythagorean triangles{{cite OEIS|A084647|Hypotenuses for which there exist exactly 3 distinct integer triangles}}
1501 = centered pentagonal number
1502 = number of pairs of consecutive integers x, x+1 such that all prime factors of both x and x+1 are at most 47{{cite OEIS|A002071|Number of pairs of consecutive integers x, x+1 such that all prime factors of both x and x+1 are at most the n-th prime}}
1503 = least number of triangles of the Spiral of Theodorus to complete 12 revolutions
1504 = primitive abundant number (abundant number all of whose proper divisors are deficient numbers)
1505 = number of integer partitions of 41 with distinct differences between successive parts{{cite OEIS|A325325|Number of integer partitions of n with distinct differences between successive parts}}
1506 = number of Golomb partitions of 28{{cite OEIS|A325858|Number of Golomb partitions of n}}
1507 = number of partitions of 32 that do not contain 1 as a part
1508 = heptagonal pyramidal number
1509 = pinwheel number
1510 = deficient number, odious number
1511 = Sophie Germain prime, balanced prime
1512 = k such that geometric mean of phi(k) and sigma(k) is an integer
1513 = centered square number
1514 = sum of first 44 composite numbers
1515 = maximum dimension of Euclidean spaces which suffice for every smooth compact Riemannian 30-manifold to be realizable as a sub-manifold
1516 = $\left \lfloor 9^\frac{10}{3} \right \rfloor$ {{cite OEIS|A018000|Powers of cube root of 9 rounded down}}
1517 = number of lattice points inside a circle of radius 22
1518 = sum of first 32 semiprimes,{{cite OEIS|A062198|Sum of first n semiprimes}} Mertens function zero
1519 = number of polyhexes with 8 cells,{{cite OEIS|A038147|Number of polyhexes with n cells}} Mertens function zero
1520 = pentagonal number, Mertens function zero, forms a Ruth–Aaron pair with 1521 under second definition
1521 = 39², Mertens function zero, centered octagonal number, forms a Ruth–Aaron pair with 1520 under second definition
1522 = k such that 5 × 2^k - 1 is prime
1523 = super-prime, Mertens function zero, safe prime, member of the Mian–Chowla sequence
1524 = Mertens function zero, k such that geometric mean of phi(k) and sigma(k) is an integer
1525 = heptagonal number, Mertens function zero
1526 = number of conjugacy classes in the alternating group A₂₇{{cite OEIS|A000702|number of conjugacy classes in the alternating group A_n}}
1527 = number of 2-dimensional partitions of 11,{{cite OEIS|A001970|Functional determinants; partitions of partitions; Euler transform applied twice to all 1's sequence}} Mertens function zero
1528 = Mertens function zero, rounded total surface area of a regular octahedron with edge length 21{{cite OEIS|A071396|Rounded total surface area of a regular octahedron with edge length n}}
1529 = composite de Polignac number
1530 = vampire number
1531 = prime number, centered decagonal number, Mertens function zero
1532 = number of series-parallel networks with 9 unlabeled edges,{{cite OEIS|A000084|Number of series-parallel networks with n unlabeled edges. Also called yoke-chains by Cayley and MacMahon}} Mertens function zero
1533 = 21 × 73 = 21 × 21st prime
1534 = number of achiral integer partitions of 50
1535 = Thabit number
1536 = a common size of microplate, 3-smooth number (2⁹×3), number of threshold functions of exactly 4 variables{{cite OEIS|A000615|Threshold functions of exactly n variables}}
1537 = Keith number, Mertens function zero
1538 = number of surface points on a cube with edge-length 17{{cite OEIS|A005897|6*n^2 + 2 for n > 0}}
1539 = maximal number of pieces that can be obtained by cutting an annulus with 54 cuts
1540 = 55th triangular number, hexagonal number, decagonal number, tetrahedral number
1541 = octagonal number
1542 = k such that 2^k starts with k{{cite OEIS|A100129|Numbers k such that 2^k starts with k}}
1543 = prime dividing all Fibonacci sequences,{{cite OEIS|A000057|Primes dividing all Fibonacci sequences}} Mertens function zero
1544 = Mertens function zero, number of partitions of integer partitions of 17 where all parts have the same length{{cite OEIS|A319066|Number of partitions of integer partitions of n where all parts have the same length}}
1545 = number of reversible string structures with 9 beads using exactly three different colors{{cite OEIS|A056327|Number of reversible string structures with n beads using exactly three different colors}}
1546 = number of 5 X 5 binary matrices with at most one 1 in each row and column,{{cite OEIS|A002720|Number of partial permutations of an n-set; number of n X n binary matrices with at most one 1 in each row and column}} Mertens function zero
1547 = hexagonal pyramidal number
1548 = coreful perfect number
1549 = de Polignac prime{{cite OEIS|A065381|Primes not of the form p + 2^k}}
1550 = $\frac {31 \times (3 \times 31 + 7)}{2}$ = number of cards needed to build a 31-tier house of cards with a flat, one-card-wide roof{{cite OEIS|A140090|n*(3*n + 7)/2}}
1551 = 6920 - 5369 = A169952(24) - A169952(23) = A169942(24) = number of Golomb rulers of length 24{{cite OEIS|A169942|Number of Golomb rulers of length n}}{{cite OEIS|A169952|Second entry in row n of triangle in A169950}}
1552 = Number of partitions of 57 into prime parts
1553 = 509 + 521 + 523 = a prime that is the sum of three consecutive primes{{cite OEIS|A034962|Primes that are the sum of three consecutive primes}}
1554 = 2 × 3 × 7 × 37 = product of four distinct primes{{cite OEIS|A046386|Products of four distinct primes}}
1555² divides 6¹⁵⁵⁴{{cite OEIS|A127106|Numbers n such that n^2 divides 6^n-1}}
1556 = sum of the squares of the first nine primes
1557 = number of graphs with 8 nodes and 13 edges{{cite OEIS|A008406|Triangle T(n,k) read by rows, giving number of graphs with n nodes and k edges)}}
1558 = number k such that k⁶⁴ + 1 is prime
1559 = Sophie Germain prime
1560 = pronic number
1561 = a centered octahedral number, number of series-reduced trees with 19 nodes{{cite OEIS|A000014|Number of series-reduced trees with n nodes}}
1562 = maximal number of regions the plane is divided into by drawing 40 circles
1563 = $\sum_{k=1}^{50} \frac{50}{\gcd(50,k)}$ {{cite OEIS|A057660|Sum_{1..n} n/gcd(n,k)}}
1564 = sum of totient function for first 71 integers
1565 = $\sqrt{1036^2+1173^2}$ and $1036+1173=47^2$ {{cite OEIS|A088319|Ordered hypotenuses of primitive Pythagorean triangles having legs that add up to a square}}
1566 = number k such that k⁶⁴ + 1 is prime
1567 = number of partitions of 24 with at least one distinct part
1568 = Achilles number{{cite OEIS|A052486|Achilles numbers}}
1569 = 2 × 28² + 1 = number of different 2 × 2 determinants with integer entries from 0 to 28
1570 = 2 × 28² + 2 = number of points on surface of tetrahedron with edgelength 28
1571 = Honaker prime
1572 = member of the Mian–Chowla sequence
1573 = discriminant of a totally real cubic field
1574²⁵⁶ + 1 is prime{{cite OEIS|A056995|Numbers k such that k^256 + 1 is prime}}
1575 = odd abundant number,{{Cite web|url=https://oeis.org/A005231|title=Sloane's A005231 : Odd abundant numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} sum of the nontriangular numbers between successive triangular numbers, number of partitions of 24
1576¹⁴ == 1 (mod 15^2){{cite OEIS|A056026|Numbers k such that k^14 is congruent with 1 (mod 15^2)}}
1577 = sum of the quadratic residues of 83{{cite OEIS|A076409|Sum of the quadratic residues of prime(n)}}
1578 = sum of first 45 composite numbers
1579 = number of partitions of 54 such that the smallest part is greater than or equal to number of parts
1580 = number of achiral integer partitions of 51
1581 = number of edges in the hexagonal triangle T(31)
1582 = a number such that the integer triangle [A070080(1582), A070081(1582), A070082(1582)] has an integer area{{cite OEIS|A070142|Numbers n such that [A070080(n), A070081(n), A070082(n)] is an integer triangle with integer area}}
1583 = Sophie Germain prime
1584 = triangular matchstick number
1585 = Riordan number, centered triangular number
1586 = area of the 23rd [https://oeis.org/A080663/a080663.jpg conjoined trapezoid]
1587 = 3 × 23² = number of edges of a complete tripartite graph of order 69, K_23,23,23{{cite OEIS|A033428|3*n^2}}
1588 = sum of totient function for first 72 integers
1589 = composite de Polignac number
1590 = rounded volume of a regular icosahedron with edge length 9{{cite OEIS|A071402|Rounded volume of a regular icosahedron with edge length n}}
1591 = rounded volume of a regular octahedron with edge length 15
1592 = sum of all divisors of the first 36 odd numbers{{cite OEIS|A326123|a(n) is the sum of all divisors of the first n odd numbers}}
1593 = sum of the first 30 primes
1594 = minimal cost of maximum height Huffman tree of size 17{{cite OEIS|A006327|Fibonacci(n) - 3. Number of total preorders}}
1595 = number of non-isomorphic set-systems of weight 10
1596 = 56th triangular number
1597 = Fibonacci prime,{{Cite web|url=https://oeis.org/A000045|title=Sloane's A000045 : Fibonacci numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} Markov prime, super-prime, emirp
1598 = number of unimodular 2 × 2 matrices having all terms in {0,1,...,25}
1599 = number of edges in the join of two cycle graphs, both of order 39

= 1600 to 1699 =

1600 = 40², structured great rhombicosidodecahedral number,{{cite OEIS|A100145|Structured great rhombicosidodecahedral numbers}} repdigit in base 7 (4444₇), street number on Pennsylvania Avenue of the White House, length in meters of a common High School Track Event, perfect score on SAT (except from 2005 to 2015)
1601 = Sophie Germain prime, Proth prime, the novel 1601 (Mark Twain)
1602 = number of points on surface of octahedron with edgelength 20
1603 = number of partitions of 27 with nonnegative rank{{cite OEIS|A064174|Number of partitions of n with nonnegative rank}}
1604 = number of compositions of 22 into prime parts{{cite OEIS|A023360|Number of compositions of n into prime parts}}
1605 = number of polyominoes consisting of 7 regular octagons{{cite OEIS|A103473|Number of polyominoes consisting of 7 regular unit n-gons}}
1606 = enneagonal pyramidal number{{cite OEIS|A007584|9-gonal (or enneagonal) pyramidal numbers}}
1607 = member of prime triple with 1609 and 1613{{cite OEIS|A022004|Initial members of prime triples (p, p+2, p+6)}}
1608 = $\sum_{k=1}^{44} \sigma(k)$
1609 = [https://oeis.org/A144391/a144391.jpg cropped hexagonal number]
1610 = number of strict partions of 43
1611 = number of rational numbers which can be constructed from the set of integers between 1 and 51
1612 = maximum dimension of Euclidean spaces which suffice for every smooth compact Riemannian 31-manifold to be realizable as a sub-manifold
1613, 1607 and 1619 are all primes{{cite OEIS|A006489|Numbers k such that k-6, k, and k+6 are primes}}
1614 = number of ways of refining the partition 8^1 to get 1^8{{cite OEIS|A213427|Number of ways of refining the partition n^1 to get 1^n}}
1615 = composite number such that the square mean of its prime factors is a nonprime integer{{cite OEIS|A134602|Composite numbers such that the square mean of their prime factors is a nonprime integer (where the prime factors are taken with multiplicity and the square mean of c and d is sqrt((c^2+d^2)/2))}}
1616 = $\frac{16(16^2 + 3 \times 16 - 1)}{3}$ = number of monotonic triples (x,y,z) in {1,2,...,16}³{{cite OEIS|A084990|n*(n^2+3*n-1)/3}}
1617 = pentagonal number
1618 = centered heptagonal number
1619 = palindromic prime in binary, safe prime
1620 = 809 + 811: sum of twin prime pair
1621 = super-prime, pinwheel number
1622 = semiprime of the form prime + 1{{cite OEIS|A077068|Semiprimes of the form prime + 1}}
1623 is not the sum of two triangular numbers and a fourth power{{cite OEIS|A115160|Numbers that are not the sum of two triangular numbers and a fourth power}}
1624 = number of squares in the Aztec diamond of order 28{{cite OEIS|A046092|4 times triangular numbers}}
1625 = centered square number
1626 = centered pentagonal number
1627 = prime and 2 × 1627 - 1 = 3253 is also prime{{cite OEIS|A005382|Primes p such that 2p-1 is also prime}}
1628 = centered pentagonal number
1629 = rounded volume of a regular tetrahedron with edge length 24
1630 = number k such that k^64 + 1 is prime
1631 = $\sum_{k=0}^{5} (k+1)! \binom{5}{k}$ {{cite OEIS|A001339|Sum_{0..n} (k+1)! binomial(n,k)}}
1632 = number of acute triangles made from the vertices of a regular 18-polygon{{cite OEIS|A007290|2*binomial(n,3)}}
1633 = star number
1634 = the smallest four-digit Narcissistic number in base 10
1635 = number of partitions of 56 whose reciprocal sum is an integer{{cite OEIS|A058360|Number of partitions of n whose reciprocal sum is an integer}}
1636 = number of nonnegative solutions to x² + y² ≤ 45²
1637 = prime island: least prime whose adjacent primes are exactly 30 apart{{cite OEIS|A046931|Prime islands: least prime whose adjacent primes are exactly 2n apart}}
1638 = harmonic divisor number,{{Cite web|url=https://oeis.org/A001599|title=Sloane's A001599 : Harmonic or Ore numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} 5 × 2¹⁶³⁸ - 1 is prime
1639 = nonagonal number
1640 = pronic number
1641 = 41² - 41 + 1 = H₄₁ (the 41st Hogben number)
1642 = maximal number of regions the plane is divided into by drawing 41 circles
1643 = sum of first 46 composite numbers
1644 = 821 + 823: sum of twin prime pair
1645 = number of 16-celled pseudo still lifes in Conway's Game of Life, up to rotation and reflection{{cite OEIS|A056613|Number of n-celled pseudo still lifes in Conway's Game of Life, up to rotation and reflection}}
1646 = number of graphs with 8 nodes and 14 edges
1647 and 1648 are both divisible by cubes{{cite OEIS|A068140|Smaller of two consecutive numbers each divisible by a cube greater than one}}
1648 = number of partitions of 34³ into distinct cubes{{cite OEIS|A030272|Number of partitions of n^3 into distinct cubes}}
1649 = highly cototient number, Leyland number using 4 & 5 (4⁵ + 5⁴)
1650 = number of cards to build an 33-tier house of cards
1651 = heptagonal number
1652 = number of partitions of 29 into a prime number of parts
1653 = 57th triangular number, hexagonal number, number of lattice points inside a circle of radius 23
1654 = number of partitions of 42 into divisors of 42{{cite OEIS|A018818|Number of partitions of n into divisors of n}}
1655 = rounded volume of a regular dodecahedron with edge length 6{{cite OEIS|A071401|Rounded volume of a regular dodecahedron with edge length n}}
1656 = 827 + 829: sum of twin prime pair
1657 = cuban prime,{{Cite web|url=https://oeis.org/A002407|title=Sloane's A002407 : Cuban primes|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} prime of the form 2p-1
1658 = smallest composite that when added to sum of prime factors reaches a prime after 25 iterations
1659 = number of rational numbers which can be constructed from the set of integers between 1 and 52
1660 = sum of totient function for first 73 integers
1661 = 11 × 151, palindrome that is a product of two palindromic primes
1662 = number of partitions of 49 into pairwise relatively prime parts
1663 = a prime number and 5¹⁶⁶³ - 4¹⁶⁶³ is a 1163-digit prime number{{cite OEIS|A059802|Numbers k such that 5^k - 4^k is prime}}
1664 = k such that k, k+1 and k+2 are sums of 2 squares{{cite OEIS|A082982|Numbers k such that k, k+1 and k+2 are sums of 2 squares}}
1665 = centered tetrahedral number
1666 = largest efficient pandigital number in Roman numerals (each symbol occurs exactly once)
1667 = 228 + 1439 and the 228th prime is 1439
1668 = number of partitions of 33 into parts all relatively prime to 33{{cite OEIS|A057562|Number of partitions of n into parts all relatively prime to n}}
1669 = super-prime, smallest prime with a gap of exactly 24 to the next prime{{cite OEIS|A000230|smallest prime p such that there is a gap of exactly 2n between p and next prime}}
1670 = number of compositions of 12 such that at least two adjacent parts are equal{{cite OEIS|A261983|Number of compositions of n such that at least two adjacent parts are equal}}
1671 divides the sum of the first 1671 composite numbers{{cite OEIS|A053781|Numbers k that divide the sum of the first k composite numbers}}
1672 = 41² - 3², the only way to express 1672 as a difference of prime squares
1673 = RMS number{{cite OEIS|A140480|RMS numbers: numbers n such that root mean square of divisors of n is an integer}}
1674 = k such that geometric mean of phi(k) and sigma(k) is an integer
1675 = Kin number{{cite OEIS|A023108|Positive integers which apparently never result in a palindrome under repeated applications of the function A056964(x)}}
1676 = number of partitions of 34 into parts each of which is used a different number of times
1677 = 41² - 2², the only way to express 1677 as a difference of prime squares
1678 = n such that n³² + 1 is prime
1679 = highly cototient number, semiprime (23 × 73, see also Arecibo message), number of parts in all partitions of 32 into distinct parts
1680 = the 17th highly composite number, number of edges in the join of two cycle graphs, both of order 40
1681 = 41², smallest number yielded by the formula n² + n + 41 that is not a prime; centered octagonal number
1682 = and 1683 is a member of a Ruth–Aaron pair (first definition)
1683 = triangular matchstick number
1684 = centered triangular number
1685 = 5-Knödel number
1686 = $\sum_{k=1}^{45} \sigma(k)$
1687 = 7-Knödel number
1688 = number of finite connected sets of positive integers greater than one with least common multiple 72{{cite OEIS|A286518|Number of finite connected sets of positive integers greater than one with least common multiple n}}
1689 = $9!!\sum_{k=0}^{4} \frac{1}{2k+1}$ {{cite OEIS|A004041|Scaled sums of odd reciprocals: (2*n + 1)!!*(Sum_{0..n} 1/(2*k + 1))}}
1690 = number of compositions of 14 into powers of 2{{cite OEIS|A023359|Number of compositions (ordered partitions) of n into powers of 2}}
1691 = the same upside down, which makes it a strobogrammatic number{{cite OEIS|A000787|Strobogrammatic numbers: the same upside down}}
1692 = coreful perfect number
1693 = smallest prime > 41².
1694 = number of unimodular 2 × 2 matrices having all terms in {0,1,...,26}
1695 = magic constant of n × n normal magic square and n-queens problem for n = 15. Number of partitions of 58 into prime parts
1696 = sum of totient function for first 74 integers
1697 = Friedlander-Iwaniec prime
1698 = number of rooted trees with 47 vertices in which vertices at the same level have the same degree
1699 = number of rooted trees with 48 vertices in which vertices at the same level have the same degree

= 1700 to 1799 =

1700 = σ₂(39): sum of squares of divisors of 39
1701 = $\left\{ {8 \atop 4} \right\}$ , decagonal number, hull number of the U.S.S. Enterprise on Star Trek
1702 = palindromic in 3 consecutive bases: 898₁₄, 787₁₅, 6A6₁₆
1703 = 1703131131 / 1000077 and the divisors of 1703 are 1703, 131, 13 and 1{{cite OEIS|A224930|Numbers n such that n divides the concatenation of all divisors in descending order}}
1704 = sum of the squares of the parts in the partitions of 18 into two distinct parts{{cite OEIS|A294286|Sum of the squares of the parts in the partitions of n into two distinct parts}}
1705 = tribonacci number{{Cite web|url=https://oeis.org/A000073|title=Sloane's A000073 : Tribonacci numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1706 = 1 + 4 + 16 + 64 + 256 + 1024 + 256 + 64 + 16 + 4 + 1 sum of fifth row of triangle of powers of 4{{cite OEIS|A020989|(5*4^n - 2)/3}}
1707 = number of partitions of 30 in which the number of parts divides 30
1708 = 2² × 7 × 61 a number whose product of prime indices 1 × 1 × 4 × 18 is divisible by its sum of prime factors 2 + 2 + 7 + 61{{cite OEIS|A331378|Numbers whose product of prime indices is divisible by their sum of prime factors}}
1709 = first of a sequence of eight primes formed by adding 57 in the middle. 1709, 175709, 17575709, 1757575709, 175757575709, 17575757575709, 1757575757575709 and 175757575757575709 are all prime, but 17575757575757575709 = 232433 × 75616446785773
1710 = maximal number of pieces that can be obtained by cutting an annulus with 57 cuts
1711 = 58th triangular number, centered decagonal number
1712 = number of irredundant sets in the 29-cocktail party graph
1713 = number of aperiodic rooted trees with 12 nodes{{cite OEIS|A301700|Number of aperiodic rooted trees with n nodes}}
1714 = number of regions formed by drawing the line segments connecting any two of the 18 perimeter points of an [https://oeis.org/A331452/a331452_20.png 3 × 6 grid of squares]{{cite OEIS|A331452|number of regions (or cells) formed by drawing the line segments connecting any two of the 2*(m+n) perimeter points of an m X n grid of squares}}
1715 = k such that geometric mean of phi(k) and sigma(k) is an integer
1716 = 857 + 859: sum of twin prime pair
1717 = pentagonal number
1718 = $\sum_{d|12} \binom{12}{d}$ {{cite OEIS|A056045|"Sum_{d divides n}(binomial(n,d))"}}
1719 = composite de Polignac number
1720 = sum of the first 31 primes
1721 = twin prime; number of squares between 42² and 42⁴.
1722 = Giuga number,{{Cite web|url=https://oeis.org/A007850|title=Sloane's A007850 : Giuga numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} pronic number
1723 = super-prime
1724 = maximal number of regions the plane is divided into by drawing 42 circles
1725 = 47² - 22² = (prime(15))² - (nonprime(15))²{{cite OEIS|A161757|(prime(n))^2 - (nonprime(n))^2}}
1726 = number of partitions of 44 into distinct and relatively prime parts{{cite OEIS|A078374|Number of partitions of n into distinct and relatively prime parts}}
1727 = area of the 24th [https://oeis.org/A080663/a080663.jpg conjoined trapezoid]
1728 = the quantity expressed as 1000 in duodecimal, that is, the cube of twelve (called a great gross), and so, the number of cubic inches in a cubic foot, palindromic in base 11 (1331₁₁) and 23 (363₂₃)
1729 = taxicab number, Carmichael number, Zeisel number, centered cube number, Hardy–Ramanujan number. In the decimal expansion of e the first time all 10 digits appear in sequence starts at the 1729th digit (or 1728th decimal place). In 1979 the rock musical Hair closed on Broadway in New York City after 1729 performances. Palindromic in bases 12, 32, 36.
1730 = 3 × 24² + 2 = number of points on surface of square pyramid of side-length 24
1731 = k such that geometric mean of phi(k) and sigma(k) is an integer
1732 = $\sum_{k=0}^5 \binom{5}{k}^k$ {{cite OEIS|A167008|Sum_{0..n} C(n,k)^k}}
1733 = Sophie Germain prime, palindromic in bases 3, 18, 19.
1734 = surface area of a cube of edge length 17{{cite OEIS|A033581|6*n^2}}
1735 = number of partitions of 55 such that the smallest part is greater than or equal to number of parts
1736 = sum of totient function for first 75 integers, number of surface points on a cube with edge-length 18
1737 = pinwheel number
1738 = number of achiral integer partitions of 52
1739 = number of 1s in all partitions of 30 into odd parts{{cite OEIS|A036469|Partial sums of A000009 (partitions into distinct parts)}}
1740 = number of squares in the Aztec diamond of order 29
1741 = super-prime, centered square number
1742 = [https://mathworld.wolfram.com/PlaneDivisionbyEllipses.html number of regions] the plane is divided into by 30 ellipses
1743 = wiener index of the windmill graph D(3,21)
1744 = k such that k, k+1 and k+2 are sums of 2 squares
1745 = 5-Knödel number
1746 = number of unit-distance graphs on 8 nodes{{cite OEIS|A350507|Number of (not necessarily connected) unit-distance graphs on n nodes}}
1747 = balanced prime
1748 = number of partitions of 55 into distinct parts in which the number of parts divides 55{{cite OEIS|A102627|Number of partitions of n into distinct parts in which the number of parts divides n}}
1749 = number of integer partitions of 33 with no part dividing all the others
1750 = hypotenuse in three different Pythagorean triangles
1751 = [https://oeis.org/A144391/a144391.jpg cropped hexagone]
1752 = 79² - 67², the only way to express 1752 as a difference of prime squares
1753 = balanced prime
1754 = k such that 5*2^k - 1 is prime
1755 = number of integer partitions of 50 whose augmented differences are distinct
1756 = centered pentagonal number
1757 = least number of triangles of the Spiral of Theodorus to complete 13 revolutions
1758 = $\sum_{k=1}^{46} \sigma(k)$
1759 = de Polignac prime
1760 = the number of yards in a mile
1761 = k such that k, k+1 and k+2 are products of two primes
1762 = number of binary sequences of length 12 and [http://neilsloane.com/doc/CNC.pdf curling number 2]{{cite OEIS|A216955|number of binary sequences of length n and curling number k}}
1763 = number of edges in the join of two cycle graphs, both of order 41
1764 = 42²
1765 = number of stacks, or planar partitions of 15{{cite OEIS|A001523|Number of stacks, or planar partitions of n; also weakly unimodal compositions of n}}
1766 = number of points on surface of octahedron with edge length 21
1767 = σ(28²) = σ(35²){{cite OEIS|A065764|Sum of divisors of square numbers}}
1768 = number of nonequivalent dissections of an hendecagon into 8 polygons by nonintersecting diagonals up to rotation{{cite OEIS|A220881|Number of nonequivalent dissections of an n-gon into n-3 polygons by nonintersecting diagonals up to rotation}}
1769 = maximal number of pieces that can be obtained by cutting an annulus with 58 cuts
1770 = 59th triangular number, hexagonal number, Seventeen Seventy, town in Australia
1771 = tetrahedral number
1772 = centered heptagonal number, sum of totient function for first 76 integers
1773 = number of words of length 5 over the alphabet {1,2,3,4,5} such that no two even numbers appear consecutively{{cite OEIS|A154964|3*a(n-1) + 6*a(n-2)}}
1774 = number of rooted identity trees with 15 nodes and 5 leaves{{cite OEIS|A055327|Triangle of rooted identity trees with n nodes and k leaves}}
1775 = $\sum_{1\leq i\leq 10}prime(i)\cdot(2\cdot i-1)$ : sum of piles of first 10 primes{{cite OEIS|A316322|Sum of piles of first n primes}}
1776 = 24th [https://oeis.org/A045944/a045944_1.jpg square star number].{{cite OEIS|A045944|Rhombic matchstick numbers: n*(3*n+2)}} The number of pieces that could be seen in a 7 × 7 × 7× 7 Rubik's Tesseract.
1777 = smallest prime > 42².
1778 = least k >= 1 such that the remainder when 6^k is divided by k is 22{{cite OEIS|A127816|least k such that the remainder when 6^k is divided by k is n}}
1779 = number of achiral integer partitions of 53
1780 = number of lattice paths from (0, 0) to (7, 7) using E (1, 0) and N (0, 1) as steps that horizontally cross the diagonal y = x with even many times{{cite OEIS|A005317|(2^n + C(2*n,n))/2}}
1781 = the first 1781 digits of e form a prime{{cite OEIS|A064118|Numbers k such that the first k digits of e form a prime}}
1782 = heptagonal number
1783 = de Polignac prime
1784 = number of subsets of {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12} such that every pair of distinct elements has a different quotient{{cite OEIS|A325860|Number of subsets of {1..n} such that every pair of distinct elements has a different quotient}}
1785 = square pyramidal number, triangular matchstick number
1786 = centered triangular number
1787 = super-prime, sum of eleven consecutive primes (137 + 139 + 149 + 151 + 157 + 163 + 167 + 173 + 179 + 181 + 191)
1788 = Euler transform of -1, -2, ..., -34{{cite OEIS|A073592|Euler transform of negative integers}}
1789 = number of wiggly sums adding to 17 (terms alternately increase and decrease or vice versa){{cite OEIS|A025047|Alternating compositions, i.e., compositions with alternating increases and decreases, starting with either an increase or a decrease}}
1790 = number of partitions of 50 into pairwise relatively prime parts
1791 = largest natural number that cannot be expressed as a sum of at most four hexagonal numbers.
1792 = Granville number
1793 = number of lattice points inside a circle of radius 24
1794 = nonagonal number, number of partitions of 33 that do not contain 1 as a part
1795 = number of heptagons with perimeter 38{{cite OEIS|A288253|Number of heptagons that can be formed with perimeter n}}
1796 = k such that geometric mean of phi(k) and sigma(k) is an integer
1797 = number k such that phi(prime(k)) is a square
1798 = 2 × 29 × 31 = 10₂ × 11101₂ × 11111₂, which yield zero when the prime factors are xored together{{cite OEIS|A235488|Squarefree numbers which yield zero when their prime factors are xored together}}
1799 = 2 × 30² − 1 = a [https://oeis.org/A056220/a056220.jpg twin square]

= 1800 to 1899 =

1800 = pentagonal pyramidal number, Achilles number, also, in da Ponte's Don Giovanni, the number of women Don Giovanni had slept with so far when confronted by Donna Elvira, according to Leporello's tally
1801 = cuban prime, sum of five and nine consecutive primes (349 + 353 + 359 + 367 + 373 and 179 + 181 + 191 + 193 + 197 + 199 + 211 + 223 + 227)
1802 = 2 × 30² + 2 = number of points on surface of tetrahedron with edge length 30, number of partitions of 30 such that the number of odd parts is a part
1803 = number of decahexes that tile the plane isohedrally but not by translation or by 180-degree rotation (Conway criterion){{cite OEIS|A075213|Number of polyhexes with n cells that tile the plane isohedrally but not by translation or by 180-degree rotation (Conway criterion)}}
1804 = number k such that k^64 + 1 is prime
1805 = number of squares between 43² and 43⁴.
1806 = pronic number, product of first four terms of Sylvester's sequence, primary pseudoperfect number,{{Cite web|url=https://oeis.org/A054377|title=Sloane's A054377 : Primary pseudoperfect numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} only number for which n equals the denominator of the nth Bernoulli number,Kellner, Bernard C.; [http://www.bernoulli.org/~bk/denombneqn.pdf 'The equation denom(B_n) = n has only one solution'] Schröder number{{Cite OEIS|1=A006318|2=Large Schröder numbers|access-date=2016-05-22}}
1807 = fifth term of Sylvester's sequence{{Cite web|url=https://oeis.org/A000058|title=Sloane's A000058 : Sylvester's sequence|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1808 = maximal number of regions the plane is divided into by drawing 43 circles
1809 = sum of first 17 super-primes{{cite OEIS|A083186|Sum of first n primes whose indices are primes}}
1810 = $\sum_{k=0}^4 \binom{4}{k}^4$ {{cite OEIS|A005260|Sum_{0..n} binomial(n,k)^4}}
1811 = Sophie Germain prime
1812 = n such that n³² + 1 is prime
1813 = number of polyominoes with 26 cells, symmetric about two orthogonal axes{{cite OEIS|A056877|Number of polyominoes with n cells, symmetric about two orthogonal axes}}
1814 = 1 + 6 + 36 + 216 + 1296 + 216 + 36 + 6 + 1 = sum of 4th row of triangle of powers of six{{cite OEIS|A061801|(7*6^n - 2)/5}}
1815 = polygonal chain number $\#(P^3_{2,1})$ {{cite OEIS|A152927|Number of sets (in the Hausdorff metric geometry) at each location between two sets defining a polygonal configuration consisting of k 4-gonal polygonal components chained with string components of length 1 as k varies}}
1816 = number of strict partions of 44
1817 = total number of prime parts in all partitions of 20{{cite OEIS|A037032|Total number of prime parts in all partitions of n}}
1818 = n such that n³² + 1 is prime
1819 = sum of the first 32 primes, minus 32{{cite OEIS|A101301|The sum of the first n primes, minus n}}
1820 = pentagonal number, pentatope number, number of compositions of 13 whose run-lengths are either weakly increasing or weakly decreasing{{cite OEIS|A332835|Number of compositions of n whose run-lengths are either weakly increasing or weakly decreasing|access-date=2022-06-02}}
1821 = member of the Mian–Chowla sequence
1822 = number of integer partitions of 43 whose distinct parts are connected
1823 = super-prime, safe prime
1824 = 43² - 5², the only way to express 1824 as a difference of prime squares
1825 = octagonal number
1826 = decagonal pyramidal number
1827 = vampire number
1828 = meandric number, open meandric number, appears twice in the first 10 decimal digits of e
1829 = composite de Polignac number
1830 = 60th triangular number
1831 = smallest prime with a gap of exactly 16 to next prime (1847){{cite OEIS|A000230|smallest prime p such that there is a gap of exactly 2n between p and next prime, or -1 if no such prime exists}}
1832 = sum of totient function for first 77 integers
1833 = number of atoms in a decahedron with 13 shells{{cite OEIS|A004068|Number of atoms in a decahedron with n shells}}
1834 = octahedral number, sum of the cubes of the first five primes
1835 = absolute value of numerator of $D_6^{(5)}$ {{cite OEIS|A001905|From higher-order Bernoulli numbers: absolute value of numerator of D-number D2n(2n-1)}}
1836 = factor by which a proton is more massive than an electron
1837 = star number
1838 = number of unimodular 2 × 2 matrices having all terms in {0,1,...,27}
1839 = $\lfloor \sqrt[3]{13!} \rfloor$ {{cite OEIS|A214083|floor(n!^(1/3))}}
1840 = 43² - 3², the only way to express 1840 as a difference of prime squares
1841 = solution to the postage stamp problem with 3 denominations and 29 stamps,{{cite OEIS|A001208|solution to the postage stamp problem with 3 denominations and n stamps}} Mertens function zero
1842 = number of unlabeled rooted trees with 11 nodes{{cite OEIS|A000081|Number of unlabeled rooted trees with n nodes (or connected functions with a fixed point)}}
1843 = k such that phi(k) is a perfect cube,{{cite OEIS|A039771|Numbers k such that phi(k) is a perfect cube}} Mertens function zero
1844 = 3⁷ - 7³,{{cite OEIS|A024026|3^n - n^3}} Mertens function zero
1845 = number of partitions of 25 containing at least one prime,{{cite OEIS|A235945|Number of partitions of n containing at least one prime}} Mertens function zero
1846 = sum of first 49 composite numbers
1847 = super-prime
1848 = number of edges in the join of two cycle graphs, both of order 42
1849 = 43², palindromic in base 6 (= 12321₆), centered octagonal number
1850 = Number of partitions of 59 into prime parts
1851 = sum of the first 32 primes
1852 = number of quantales on 5 elements, up to isomorphism{{cite OEIS|A354493|Number of quantales on n elements, up to isomorphism}}
1853 = sum of primitive roots of 27-th prime,{{cite OEIS|A088144|Sum of primitive roots of n-th prime}} Mertens function zero
1854 = number of permutations of 7 elements with no fixed points,{{cite OEIS|A000166|Subfactorial or rencontres numbers, or derangements: number of permutations of n elements with no fixed points}} Mertens function zero
1855 = rencontres number: number of permutations of [7] with exactly one fixed point{{cite OEIS|A000240|Rencontres numbers: number of permutations of [n] with exactly one fixed point}}
1856 = sum of totient function for first 78 integers
1857 = Mertens function zero, pinwheel number
1858 = number of 14-carbon alkanes C₁₄H₃₀ ignoring stereoisomers{{cite OEIS|A000602|Number of n-node unrooted quartic trees; number of n-carbon alkanes C(n)H(2n+2) ignoring stereoisomers}}
1859 = composite de Polignac number
1860 = number of squares in the Aztec diamond of order 30{{cite web|url=https://mathworld.wolfram.com/AztecDiamond.html|title="Aztec Diamond"|access-date=2022-09-20}}
1861 = centered square number, Mertens function zero
1862 = Mertens function zero, forms a Ruth–Aaron pair with 1863 under second definition
1863 = Mertens function zero, forms a Ruth–Aaron pair with 1862 under second definition
1864 = Mertens function zero, $\frac{1864!-2}{2}$ is a prime{{cite OEIS|A082671|Numbers n such that (n!-2)/2 is a prime}}
1865 = 12345₆: Largest senary metadrome (number with digits in strict ascending order in base 6){{cite OEIS|A023811|Largest metadrome (number with digits in strict ascending order) in base n}}
1866 = Mertens function zero, number of plane partitions of 16 with at most two rows{{cite OEIS|A000990|Number of plane partitions of n with at most two rows}}
1867 = prime de Polignac number
1868 = smallest number of complexity 21: smallest number requiring 21 1's to build using +, * and ^
1869 = Hultman number: S_H(7, 4){{cite OEIS|A164652|Hultman numbers}}
1870 = decagonal number
1871 = the first prime of the 2 consecutive twin prime pairs: (1871, 1873) and (1877, 1879){{cite OEIS|A007530|Prime quadruples: numbers k such that k, k+2, k+6, k+8 are all prime}}
1872 = first Zagreb index of the complete graph K₁₃
1873 = number of Narayana's cows and calves after 21 years
1874 = area of the 25th [https://oeis.org/A080663/a080663.jpg conjoined trapezoid]
1875 = 50² - 25²
1876 = number k such that k^64 + 1 is prime
1877 = number of partitions of 39 where 39 divides the product of the parts{{cite OEIS|A057568|Number of partitions of n where n divides the product of the parts}}
1878 = n such that n³² + 1 is prime
1879 = a prime with square index{{cite OEIS|A011757|prime(n^2)}}
1880 = the 10th element of the self convolution of Lucas numbers{{cite OEIS|A004799|Self convolution of Lucas numbers}}
1881 = tricapped prism number{{cite OEIS|A005920|Tricapped prism numbers}}
1882 = number of linearly separable Boolean functions in 4 variables{{cite OEIS|A000609|Number of threshold functions of n or fewer variables}}
1883 = number of conjugacy classes in the alternating group A₂₈
1884 = k such that 5*2^k - 1 is prime
1885 = Zeisel number
1886 = number of partitions of 6⁴ into fourth powers{{cite OEIS|A259793|Number of partitions of n^4 into fourth powers}}
1887 = number of edges in the hexagonal triangle T(34)
1888 = primitive abundant number (abundant number all of whose proper divisors are deficient numbers)
1889 = Sophie Germain prime, highly cototient number
1890 = triangular matchstick number
1891 = 61st triangular number, sum of 5 consecutive primes ({{math|1=367 + 373 + 379 + 383 + 389}}) hexagonal number, centered pentagonal number, centered triangular number
1892 = pronic number
1893 = 44² - 44 + 1 = H₄₄ (the 44th Hogben number)
1894 = maximal number of regions the plane is divided into by drawing 44 circles
1895 = Stern-Jacobsthal number
1896 = member of the Mian-Chowla sequence
1897 = member of Padovan sequence, number of triangle-free graphs on 9 vertices{{cite OEIS|A006785|Number of triangle-free graphs on n vertices}}
1898 = smallest multiple of n whose digits sum to 26{{cite OEIS|A002998|Smallest multiple of n whose digits sum to n}}
1899 = [https://oeis.org/A144391/a144391.jpg cropped hexagone]

= 1900 to 1999 =

1900 = number of primes <= 2¹⁴
1901 = Sophie Germain prime, centered decagonal number
1902 = number of symmetric plane partitions of 27{{cite OEIS|A005987|Number of symmetric plane partitions of n}}
1903 = generalized Catalan number{{cite OEIS|A023431|Generalized Catalan Numbers}}
1904 = number of flat partitions of 43
1905 = Fermat pseudoprime
1906 = number n such that 3ⁿ - 8 is prime{{cite OEIS|A217135|Numbers n such that 3^n - 8 is prime}}
1907 = safe prime, balanced prime
1908 = coreful perfect number
1909 = hyperperfect number{{Cite web|url=https://oeis.org/A034897|title=Sloane's A034897 : Hyperperfect numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}}
1910 = number of compositions of 13 having exactly one fixed point{{cite OEIS|A240736|Number of compositions of n having exactly one fixed point}}
1911 = heptagonal pyramidal number
1912 = size of 6th maximum raising after one blind in pot-limit poker{{cite OEIS|A007070|4*a(n-1) - 2*a(n-2)}}
1913 = super-prime, Honaker prime
1914 = number of bipartite partitions of 12 white objects and 3 black ones{{cite OEIS|A000412|Number of bipartite partitions of n white objects and 3 black ones}}
1915 = number of nonisomorphic semigroups of order 5{{cite OEIS|A027851|Number of nonisomorphic semigroups of order n}}
1916 = sum of first 50 composite numbers
1917 = number of partitions of 51 into pairwise relatively prime parts
1918 = heptagonal number
1919 = smallest number with reciprocal of period length 36 in base 10{{cite OEIS|A003060|Smallest number with reciprocal of period length n in decimal (base 10)}}
1920 = sum of the nontriangular numbers between successive triangular numbers 120 and 136,
1921 = 4-dimensional centered cube number{{cite OEIS|A008514|4-dimensional centered cube numbers}}
1922 = Area of a square with diagonal 62
1923 = 2 × 31² + 1 = number of different 2 X 2 determinants with integer entries from 0 to 31
1924 = 2 × 31² + 2 = number of points on surface of tetrahedron with edge length 31, sum of the first 36 semiprimes{{cite OEIS|A062198|Sum of the first n semiprimes}}
1925 = number of ways to write 24 as an orderless product of orderless sums
1926 = pentagonal number
1927 = 2¹¹ - 11²{{cite OEIS|A024012|2^n - n^2}}
1928 = number of distinct values taken by 2^2^...^2 (with 13 2's and parentheses inserted in all possible ways){{cite OEIS|A002845|Number of distinct values taken by 2^2^...^2 (with n 2's and parentheses inserted in all possible ways)}}
1929 = Mertens function zero, number of integer partitions of 42 whose distinct parts are connected
1930 = number of pairs of consecutive integers x, x+1 such that all prime factors of both x and x+1 are at most 53
1931 = Sophie Germain prime
1932 = number of partitions of 40 into prime power parts
1933 = centered heptagonal number, Honaker prime
1934 = sum of totient function for first 79 integers
1935 = number of edges in the join of two cycle graphs, both of order 43
1936 = 44², 18-gonal number,{{Cite web|url=https://oeis.org/A051870|title=Sloane's A051870 : 18-gonal numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-12}} 324-gonal number.
1937 = number of chiral n-ominoes in 12-space, one cell labeled{{cite OEIS|A045648|Number of chiral n-ominoes in (n-1)-space, one cell labeled}}
1938 = Mertens function zero, number of points on surface of octahedron with edge length 22
1939 = 7-Knödel number
1940 = the Mahonian number: T(8, 9)
1941 = maximal number of regions obtained by joining 16 points around a circle by straight lines{{cite OEIS|A000127|Maximal number of regions obtained by joining n points around a circle by straight lines. Also number of regions in 4-space formed by n-1 hyperplanes}}
1942 = number k for which 10k + 1, 10k + 3, 10k + 7, 10k + 9 and 10k + 13 are primes{{cite OEIS|A178084|Numbers k for which 10k + 1, 10k + 3, 10k + 7, 10k + 9 and 10k + 13 are primes}}
1943 = largest number not the sum of distinct tetradecagonal numbers{{cite OEIS|A007419|Largest number not the sum of distinct n-th-order polygonal numbers}}
1944 = 3-smooth number (2³×3⁵), Achilles number
1945 = number of partitions of 25 into relatively prime parts such that multiplicities of parts are also relatively prime{{cite OEIS|A100953|Number of partitions of n into relatively prime parts such that multiplicities of parts are also relatively prime}}
1946 = number of surface points on a cube with edge-length 19
1947 = k such that 5·2^k + 1 is a prime factor of a Fermat number 2^{2^m} + 1 for some m{{cite OEIS|A226366|Numbers k such that 5*2^k + 1 is a prime factor of a Fermat number 2^(2^m) + 1 for some m}}
1948 = number of strict solid partitions of 20
1949 = smallest prime > 44².
1950 = $1 \cdot 2 \cdot 3 + 4 \cdot 5 \cdot 6 + 7 \cdot 8 \cdot 9 + 10 \cdot 11 \cdot 12$ ,{{cite OEIS|A319014|1*2*3 + 4*5*6 + 7*8*9 + 10*11*12 + 13*14*15 + 16*17*18 + ... + (up to n)}} largest number not the sum of distinct pentadecagonal numbers
1951 = cuban prime
1952 = number of covers of {1, 2, 3, 4}{{cite OEIS|A055621|Number of covers of an unlabeled n-set}}
1953 = hexagonal prism number,{{cite OEIS|A005915|Hexagonal prism numbers}} 62nd triangular number
1954 = number of sum-free subsets of {1, ..., 16}
1955 = number of partitions of 25 with at least one distinct part
1956 = nonagonal number
1957 = $\sum_{k=0}^{6} \frac{6!}{k!}$ = total number of ordered k-tuples (k=0,1,2,3,4,5,6) of distinct elements from an 6-element set{{cite OEIS|A000522|Total number of ordered k-tuples of distinct elements from an n-element set}}
1958 = number of partitions of 25
1959 = Heptanacci-Lucas number{{cite OEIS|A104621|Heptanacci-Lucas numbers}}
1960 = number of parts in all partitions of 33 into distinct parts
1961 = number of lattice points inside a circle of radius 25
1962 = number of edges in the join of the complete graph K₃₆ and the cycle graph C₃₆{{cite OEIS|A005449|Second pentagonal numbers}}
1963! - 1 is prime{{cite OEIS|A002982|Numbers n such that n! - 1 is prime}}
1964 = number of linear forests of planted planar trees with 8 nodes{{cite OEIS|A030238|Backwards shallow diagonal sums of Catalan triangle A009766}}
1965 = total number of parts in all partitions of 17
1966 = sum of totient function for first 80 integers
1967 = least edge-length of a square dissectable into at least 30 squares in the Mrs. Perkins's quilt problem{{cite OEIS|A089046|Least edge-length of a square dissectable into at least n squares in the Mrs. Perkins's quilt problem}}
σ(1968) = σ(1967) + σ(1966){{cite OEIS|A065900|Numbers n such that sigma(n) equals sigma(n-1) + sigma(n-2)}}
1969 = Only value less than four million for which a "mod-ification" of the standard Ackermann Function does not stabilize{{cite journal

| title=A Mod-n Ackermann Function, or What's So Special About 1969?

| url=https://archive.org/details/sim_american-mathematical-monthly_1993-02_100_2/page/180

| author=Jon Froemke

| author2=Jerrold W. Grossman

| name-list-style=amp|journal=The American Mathematical Monthly

| volume=100|issue=2|date=Feb 1993|pages= 180–183

| publisher=Mathematical Association of America

| jstor=2323780|doi=10.2307/2323780}}

1970 = number of compositions of two types of 9 having no even parts{{cite OEIS|A052542|2*a(n-1) + a(n-2)}}
1971 = $3^7-6^3$ {{cite OEIS|A024069|6^n - n^7}}
1972 = n such that $\frac{n^{37}-1}{n-1}$ is prime{{cite OEIS|A217076|Numbers n such that (n^37-1)/(n-1) is prime}}
{{anchor|1973}} 1973 = Sophie Germain prime, Leonardo prime
1974 = number of binary vectors of length 17 containing no singletons
1975 = number of partitions of 28 with nonnegative rank
1976 = octagonal number
1977 = number of non-isomorphic multiset partitions of weight 9 with no singletons{{cite OEIS|A302545|Number of non-isomorphic multiset partitions of weight n with no singletons}}
1978 = n such that n | (3ⁿ + 5){{cite OEIS|A277288|Positive integers n such that n divides (3^n + 5)}}
1979 = number of squares between 45² and 45⁴, smallest number that is the sum of 4 positive cubes in at least 4 ways{{cite OEIS|A343971|Numbers that are the sum of four positive cubes in four or more ways}}
1980 = pronic number, highly abundant number with a greater sum of proper divisors than all smaller numbers{{cite OEIS|A034090|Numbers k whose sum of proper divisors exceeds that of all smaller numbers}}
1981 = pinwheel number, central polygonal number
1982 = maximal number of regions the plane is divided into by drawing 45 circles, a number with the property that 3¹⁹⁸² - 1982 is prime{{cite OEIS|A058037|Numbers k such that 3^k - k is prime}}
1983 = skiponacci number
1984 = 11111000000 in binary, nonunitary perfect number,{{cite OEIS|A064591|Nonunitary perfect numbers}} see also: 1984 (disambiguation)
1985 = centered square number
1986 = number of ways to write 25 as an orderless product of orderless sums
1987 = 300th prime number
1988 = sum of the first 33 primes,{{cite OEIS|A007504|Sum of the first n primes}} sum of the first 51 composite numbers{{cite OEIS|A053767|Sum of the first n composite numbers}}
1989 = number of balanced primes less than 100,000,{{cite OEIS|A096711|Number of balanced primes less than 10^n.}} number of 9-step mappings with 4 inputs
1990 = Stella octangula number
1991 = 11 × 181, the 46th Gullwing number,{{cite OEIS|A187220|Gullwing sequence}} palindromic composite number with only palindromic prime factors{{cite OEIS|A046351|Palindromic composite numbers with only palindromic prime factors}}
1992 = number of nonisomorphic sets of nonempty subsets of a 4-set{{cite OEIS|A000612|Number of P-equivalence classes of switching functions of n or fewer variables, divided by 2}}
1993 = a number with the property that 4¹⁹⁹³ - 3¹⁹⁹³ is prime,{{oeis|A059801}} number of partitions of 30 into a prime number of parts
1994 = Glaisher's function W(37){{cite OEIS|A002470|Glaisher's function W(n)}}
1995 = number of unlabeled graphs on 9 vertices with independence number 6{{cite OEIS|A263341|Triangle read by rows: T(n,k) is the number of unlabeled graphs on n vertices with independence number k}}
1996 = a number with the property that (1996! + 3)/3 is prime{{cite OEIS|A089085|Numbers k such that (k! + 3)/3 is prime}}
1997 = $\sum_{k=1}^{21} {k \cdot \phi(k)}$ {{cite OEIS|A011755|Sum_{1..n} k*phi(k)}}
1998 = triangular matchstick number
1999 = centered triangular number,{{cite OEIS|A005448|Centered triangular numbers: 3n(n-1)/2 + 1}} number of regular forms in a myriagram.

= Prime numbers =

There are 135 prime numbers between 1000 and 2000:{{Cite OEIS|A038823|Number of primes between n*1000 and (n+1)*1000}}{{cite web |last=Stein |first=William A. |author-link=William A. Stein |title=The Riemann Hypothesis and The Birch and Swinnerton-Dyer Conjecture |url=https://wstein.org/talks/2017-02-10-wing-rh_and_bsd/ |website=wstein.org |date=10 February 2017 |access-date=6 February 2021}}

:1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223, 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373, 1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451, 1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511, 1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583, 1597, 1601, 1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657, 1663, 1667, 1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733, 1741, 1747, 1753, 1759, 1777, 1783, 1787, 1789, 1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871, 1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973, 1979, 1987, 1993, 1997, 1999

Notes

References

Category:Integers