id:A128597 - OEIS Search Results

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Column 2 of triangle A128596; a(n) = coefficient of q^(2n+4) in the q-analog of the even double factorials (2n+4)!! for n>=0.

+0
3

1, 7, 46, 297, 1919, 12399, 80241, 520399, 3382588, 22034519, 143826980, 940569228, 6161492611, 40426009162, 265617089899, 1747501590554, 11510584144337, 75901841055650, 501007227527884, 3310076954166501 (list; graph; listen)

	OFFSET	`0,2`
	FORMULA	`a(n) = [q^(2n+4)] Product_{j=1..n+2} (1-q^(2j))/(1-q) for n>=0.`
	PROGRAM	`(PARI) {a(n)=polcoeff(prod(j=1, n+2, (1-q^(2j))/(1-q)), 2n+4, q)}`
	CROSSREFS	`Cf. A128596; A128084; A000165 ((2n)!!); A128086 (column 1), A128598 (column 3).` `Sequence in context: A100024 A086092 A081894 this_sequence A067318 A072948 A000823` `Adjacent sequences: A128594 A128595 A128596 this_sequence A128598 A128599 A128600`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Mar 12 2007`

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Last modified December 6 13:45 EST 2009. Contains 170429 sequences.

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