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A014629
Number of segments created by diagonals of n-gon.
0
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
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
KEYWORD
nonn,easy
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