323 (number)
323 (three hundred [and] twenty-three) is the natural number following 322 and preceding 324.
{{Infobox number|cardinal=three hundred twenty three|ordinal=323d
(three hundred twenty-third)|factorization=17 × 19|divisor=1, 17, 19, 323|roman=CCCXXIII}}
In mathematics
- 323 is a semiprime, and the product of two consecutive prime numbers (17 × 19).
- 323 is the sum of nine consecutive primes (19 + 23 + 29 + 31 + 37 + 41 + 43 + 47 + 53) and the sum of the 13 consecutive primes (5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47)
- 323 is the eighth Motzkin number, , meaning there are 323 ways to draw non-intersecting chords between eight points on a circle.{{Cite OEIS|A001006|2=Motzkin numbers: number of ways of drawing any number of nonintersecting chords joining n (labeled) points on a circle.}}
- 323 is the first Lucas pseudoprime with parameters (P, Q) defined by Selfridge's method.{{Cite OEIS|A217120|2=Lucas pseudoprimes.}}{{Cite journal |last=Baillie |first=Robert |last2=Wagstaff |first2=Samuel S. |date=1980 |title=Lucas pseudoprimes |url=https://www.ams.org/journals/mcom/1980-35-152/S0025-5718-1980-0583518-6/ |journal=Mathematics of Computation |language=en |volume=35 |issue=152 |pages=1391–1417 |doi=10.1090/S0025-5718-1980-0583518-6 |issn=0025-5718}}
- 323 is the first Fibonacci pseudoprime (Lucas pseudoprime with P = 1 and Q = -1).{{Cite OEIS|A081264|2=Odd Fibonacci pseudoprimes: odd composite numbers k such that either (1) k divides Fibonacci(k-1) if k == +-1 (mod 5) or (2) k divides Fibonacci(k+1) if k == +-2 (mod 5).}}