A096191 a(n) = Sum_{k=1..n} C(n,k)^3 where C(n,k) is binomial(n,k).

1, 9, 55, 345, 2251, 15183, 104959, 739161, 5280931, 38165259, 278415919, 2046924399, 15148345759, 112738423359, 843126957055, 6332299624281, 47737325577619, 361077477684435, 2739270870994735, 20836827035351595

Offset: 1

Author

Gerald McGarvey, Jul 25 2004

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..200

Crossrefs

Equals A000172(n) - 1.

Programs

Mathematica

Table[Sum[Binomial[n,k]^3,{k,n}],{n,20}] (* Harvey P. Dale, Jul 19 2011 *)

Formula

a(n) ~ 2^(3*n+1) / (sqrt(3)*Pi*n). - Vaclav Kotesovec, Nov 27 2017