A201106 a(n) = binomial(n^2,3)/(2*n).

0, 1, 14, 70, 230, 595, 1316, 2604, 4740, 8085, 13090, 20306, 30394, 44135, 62440, 86360, 117096, 156009, 204630, 264670, 338030, 426811, 533324, 660100, 809900, 985725, 1190826, 1428714, 1703170, 2018255, 2378320, 2788016, 3252304, 3776465, 4366110, 5027190

Offset: 1

Author

Gary Detlefs, Nov 26 2011

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).

Crossrefs

Cf. A264853 (first differences).

Programs

Maple

seq(binomial(n^2,3)/(2*n), n=1..29)

Formula

a(n) = (n-1)*n*(n^3+n^2-2*n-2)/12.

G.f.: x^2*(1+8*x+x^2) / (x-1)^6. - R. J. Mathar, Nov 28 2011