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%I #11 Nov 27 2017 11:01:55
%S 1,9,55,345,2251,15183,104959,739161,5280931,38165259,278415919,
%T 2046924399,15148345759,112738423359,843126957055,6332299624281,
%U 47737325577619,361077477684435,2739270870994735,20836827035351595
%N a(n) = Sum_{k=1..n} C(n,k)^3 where C(n,k) is binomial(n,k).
%H Vincenzo Librandi, <a href="/A096191/b096191.txt">Table of n, a(n) for n = 1..200</a>
%F a(n) ~ 2^(3*n+1) / (sqrt(3)*Pi*n). - _Vaclav Kotesovec_, Nov 27 2017
%t Table[Sum[Binomial[n,k]^3,{k,n}],{n,20}] (* _Harvey P. Dale_, Jul 19 2011 *)
%Y Equals A000172(n) - 1.
%K nonn
%O 1,2
%A _Gerald McGarvey_, Jul 25 2004