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A128594 Column 2 of triangle A128592; a(n) = coefficient of q^(2n+6) in the q-analog of the odd double factorials (2n+5)!! for n>=0. 3
1, 12, 97, 696, 4784, 32230, 214978, 1426566, 9441417, 62405645, 412278981, 2723566163, 17996243101, 118957645301, 786700165122, 5205396517853, 34461624895701, 228274455988134, 1512920531980961, 10032446308837778 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..19.

FORMULA

a(n) = [q^(2n+6)] Product_{j=1..n+3} (1-q^(2j-1))/(1-q) for n>=0.

PROG

(PARI) {a(n)=polcoeff(prod(j=1, n+3, (1-q^(2*j-1))/(1-q)), 2*n+6, q)}

CROSSREFS

Cf. A128592; A128080; A001147 ((2n-1)!!); A128593 (column 1), A128595 (row sums).

Sequence in context: A078605 A021029 A270496 * A166793 A041268 A216028

Adjacent sequences:  A128591 A128592 A128593 * A128595 A128596 A128597

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 12 2007

STATUS

approved

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Last modified May 15 10:54 EDT 2021. Contains 343909 sequences. (Running on oeis4.)