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

0,2

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.

Links

Table of n, a(n) for n=0..13.

Prog

(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))}

Crossrefs

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

Sequence in context: A015015 A355132 A355133 * A365355 A139225 A356610

Adjacent sequences: A128084 A128085 A128086 * A128088 A128089 A128090

Keyword

nonn

Author

Paul D. Hanna, Feb 14 2007

Status

approved