A014629 Number of segments created by diagonals of n-gon.

0, 4, 15, 39, 84, 160, 279, 455, 704, 1044, 1495, 2079, 2820, 3744, 4879, 6255, 7904, 9860, 12159, 14839, 17940, 21504, 25575, 30199, 35424, 41300, 47879, 55215, 63364, 72384, 82335, 93279, 105280, 118404, 132719, 148295, 165204, 183520

Offset

1,2

Links

Table of n, a(n) for n=1..38.

Formula

a(n) = (n^4+2*n^3+5*n^2+4*n-12)/12. [adapted to offset by Gionata Neri, Feb 06 2021]

G.f.: x^2*(-4+5*x-4*x^2+x^3)/(x-1)^5. - Maksym Voznyy (voznyy(AT)mail.ru), Aug 10 2009

Crossrefs

Sequence in context: A209409 A241302 A112666 * A062486 A193226 A291555

Adjacent sequences: A014626 A014627 A014628 * A014630 A014631 A014632

Keyword

nonn,easy

Author

Mohammad K. Azarian

Extensions

G.f. proposed by Maksym Voznyy checked and corrected by R. J. Mathar, Sep 16 2009

More terms from Erich Friedman

Offset corrected by Mohammad K. Azarian, Nov 19 2008

Status

approved