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A128087 Sum of squared coefficients of q in the q-analog of the even double factorials. 2

%I

%S 1,2,14,296,12938,956720,107245250,16966970200,3601980861720,

%T 988252809411908,340375635448973106,143798619953044471444,

%U 73123320014581106403732,44060303354020797873285800

%N Sum of squared coefficients of q in the q-analog of the even double factorials.

%C See A128083 for sum of squared coefficients of q in the q-analog of the odd double factorials. Also, A127728 is the sum of squared coefficients of q in the q-factorials.

%o (PARI) {a(n)=if(n==0,1,sum(k=0,n^2,polcoeff(prod(j=1,n,(1-q^(2*j))/(1-q)),k,q)^2))}

%Y Cf. A000165 ((2n)!!); A128084 (triangle), A128085 (central terms), A128086 (diagonal); A127728.

%K nonn

%O 0,2

%A _Paul D. Hanna_, Feb 14 2007

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Last modified August 4 21:21 EDT 2021. Contains 346455 sequences. (Running on oeis4.)