id:A073584 - OEIS Search Results

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Commuting even permutations: number of ordered pairs g, h in the alternating group A_n such that gh = hg.

+0
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1, 1, 9, 48, 300, 2520, 22680, 282240, 3265920, 43545600, 618710400, 10298534400, 171243072000, 3138418483200, 61460695296000, 1286751578112000, 27743619391488000, 640237370572800000, 15448927751921664000, 394130125324615680000, 10422552203028725760000, 288306186674956369920000 (list; graph; listen)

	OFFSET	`1,3`
	LINKS	`N. J. A. Sloane, Table of n, a(n) for n = 1..37`
	FORMULA	`For n>=2 : a(n) = (n!/2) * A000702(n).`
	CROSSREFS	`Cf. A000702, A053529.` `Sequence in context: A055582 A054460 A115053 this_sequence A007037 A140891 A072461` `Adjacent sequences: A073581 A073582 A073583 this_sequence A073585 A073586 A073587`
	KEYWORD	`nonn`
	AUTHOR	`Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 13 2003`
	EXTENSIONS	`More terms from N. J. A. Sloane (njas(AT)research.att.com) (based on A000720), Dec 31 2006`

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Last modified December 20 16:54 EST 2009. Contains 171081 sequences.

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