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A130857 a(n) = (n-1)*n*(n+1)*(n+2)*(2n+11)/120. 0

%I

%S 0,3,17,57,147,322,630,1134,1914,3069,4719,7007,10101,14196,19516,

%T 26316,34884,45543,58653,74613,93863,116886,144210,176410,214110,

%U 257985,308763,367227,434217,510632,597432,695640,806344,930699,1069929

%N a(n) = (n-1)*n*(n+1)*(n+2)*(2n+11)/120.

%C The motivation for this sequence is the triple sum Sum[Sum[Sum[k^2-1,{k,1,m}],{m,1,j}],{j,1,n}], which can be simplified into the polynomial term given as definition.

%F G.f.: -x^2*(x-3)/(-1+x)^6. - _R. J. Mathar_, Nov 14 2007

%t Table[(n - 1)*n(n + 1)*(n + 2)*(2*n + 11)/120, {n, 1, 35}]

%t Times@@#*(2#[[2]]+11)/120&/@Partition[Range[0,40],4,1] (* _Harvey P. Dale_, Oct 28 2012 *)

%Y Cf. A117662.

%K nonn

%O 1,2

%A _Roger L. Bagula_, Jul 22 2007

%E Edited and extended by _N. J. A. Sloane_, Jul 26 2007

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Last modified August 1 19:14 EDT 2021. Contains 346402 sequences. (Running on oeis4.)