A011913 a(n) = floor(n*(n - 1)*(n - 2)/31).

0, 0, 0, 0, 0, 1, 3, 6, 10, 16, 23, 31, 42, 55, 70, 88, 108, 131, 157, 187, 220, 257, 298, 342, 391, 445, 503, 566, 634, 707, 785, 870, 960, 1056, 1158, 1266, 1381, 1503, 1632, 1768, 1912, 2063, 2221, 2388, 2563

Offset

0,7

Links

Table of n, a(n) for n=0..44.

Index entries for linear recurrences with constant coefficients, signature (3, -3, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -3, 3, -1).

Formula

G.f.: (x^5*(1 + x^4*(1 + x*(-1 + x^2*(2 + x*(-1 + x^2*(1 + x*(-1 + x + x^3 - x^4 + x^5 - x^7 + 2*x^8 - x^10 + x^11 + 2*x^15 - 2*x^16 + x^17))))))))/(1 + x*(-3 + x*(3 + x*(-1 + (-1 + x)^3*x^28)))). - Peter J. C. Moses, Jun 02 2014

Prog

(PARI) a(n) = n*(n-1)*(n-2)\31 \\ Jianing Song, Oct 15 2018

Crossrefs

Sequence in context: A180746 A025714 A025729 * A024531 A034198 A121776

Adjacent sequences: A011910 A011911 A011912 * A011914 A011915 A011916

Keyword

nonn

Author

N. J. A. Sloane.

Status

approved