A128083 Sum of squared coefficients of q in the q-analog of the odd double factorials.

1, 1, 3, 37, 1159, 66953, 6158021, 825889193, 152147002939, 36866098462221, 11368538145120143, 4347671960639941039, 2019396728684584627337, 1119792551093682455434255, 730724550040451849614251167

Offset: 0

Author

Paul D. Hanna, Feb 14 2007

Keywords

• nonn

Crossrefs

Cf. A001147 ((2n-1)!!); A128080 (triangle), A128081 (central terms), A128082 (diagonal); A127728, A128087.

Programs

PARI

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