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

1, 2, 14, 296, 12938, 956720, 107245250, 16966970200, 3601980861720, 988252809411908, 340375635448973106, 143798619953044471444, 73123320014581106403732, 44060303354020797873285800

Offset: 0

Author

Paul D. Hanna, Feb 14 2007

Keywords

• nonn

Comments

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.

Crossrefs

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

Programs

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))}