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Search: id:A128087
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| A128087 |
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Sum of squared coefficients of q in the q-analog of the even double factorials. |
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+0
3
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| 1, 2, 14, 296, 12938, 956720, 107245250, 16966970200, 3601980861720, 988252809411908, 340375635448973106, 143798619953044471444, 73123320014581106403732, 44060303354020797873285800
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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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.
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PROGRAM
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(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))}
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CROSSREFS
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Cf. A000165 ((2n)!!); A128084 (triangle), A128085 (central terms), A128086 (diagonal); A127728.
Sequence in context: A018803 A132695 A015015 this_sequence A139225 A078675 A165696
Adjacent sequences: A128084 A128085 A128086 this_sequence A128088 A128089 A128090
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Feb 14 2007
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