centered heptagonal number

{{Short description|Centered figurate number that represents a heptagon with a dot in the center}}

{{Use American English|date=March 2021}}

{{Use mdy dates|date=March 2021}}

Image:Centered heptagonal number.svg

A centered heptagonal number is a centered figurate number that represents a heptagon with a dot in the center and all other dots surrounding the center dot in successive heptagonal layers. The centered heptagonal number for n is given by the formula

:$\{7n^2\; -\; 7n\; +\; 2\}\backslash over2$.

The first few centered heptagonal numbers are

1, 8, 22, 43, 71, 106, 148, 197, 253, 316, 386, 463, 547, 638, 736, 841, 953{{cite OEIS|A069099|Centered heptagonal numbers}}