Nonagonal Number


A polygonal number of the form N_n=n(7n-5)/2, also called an enneagonal number. The first few are 1, 9, 24, 46, 75, 111, 154, 204, ... (OEIS A001106). The generating function for the nonagonal numbers is


The first few odd nonagonal numbers are 1, 9, 75, 111, 261, 325, ... (OEIS A028991), and the first few even nonagonal numbers are 24, 46, 154, 204, 396, ... (OEIS A028992).

See also

Figurate Number, Nonagonal Heptagonal Number, Nonagonal Hexagonal Number, Nonagonal Octagonal Number, Nonagonal Pentagonal Number, Nonagonal Square Number, Nonagonal Triangular Number, Polygonal Number

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Sloane, N. J. A. Sequences A001106/M4604, A028991, and A028992 in "The On-Line Encyclopedia of Integer Sequences."

Referenced on Wolfram|Alpha

Nonagonal Number

Cite this as:

Weisstein, Eric W. "Nonagonal Number." From MathWorld--A Wolfram Web Resource.

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