- 2024-02-28. Sloane, N. J. A. (ed.). "Sequence A051871 (19-gonal (or
enneadecagonal) numbers: n(17n-15)/2.)". The On-Line
Encyclopedia of
Integer Sequences...
- 585 730 4/7 ln 2 − √2/14 ln (3 − 2√2) + π(1 + √2)/14 A051870 19
Enneadecagonal 1/2(17n2 − 15n) 1 19 54 106 175 261 364 484 621 775 A051871 20 Icosagonal...