Nonagonal numbers are figurate numbers based on a 9-sided polygon, given by \(N_k = k(7k-5)/2\) for \(k \geq 1\). First terms: 1, 9, 24, 46, 75, 111, 154, 204, 261, 325.
Term
Nonagonal
Figurate numbers k(7k−5)/2 (1, 9, 24, 46, 75, 111, 154, 204, …).
23 numbers tagged.