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A128087 Sum of squared coefficients of q in the q-analog of the even double factorials. 2
1, 2, 14, 296, 12938, 956720, 107245250, 16966970200, 3601980861720, 988252809411908, 340375635448973106, 143798619953044471444, 73123320014581106403732, 44060303354020797873285800 (list; graph; refs; listen; history; text; internal format)
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: A217474 A132695 A015015 * A139225 A277035 A078675

Adjacent sequences:  A128084 A128085 A128086 * A128088 A128089 A128090

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Feb 14 2007

STATUS

approved

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Last modified March 20 15:43 EDT 2019. Contains 321345 sequences. (Running on oeis4.)