id:A026739 - OEIS Search Results

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Number of subgroups L of Z^n with the property that for every a in Z^n there exists precisely one b in L with d(a,b) <= 1. Here d denotes Euclidean distance.

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1, 1, 2, 8, 72, 384, 3840, 80640, 645120, 10321920, 309657600, 3715891200, 102187008000, 3310859059200, 51011754393600, 1428329123020800, 68559797904998400, 1942527607308288000 (list; graph; listen)

	OFFSET	`0,3`
	FORMULA	`a(n)=2^nn!sum(1/\|Aut(G)\|), where the sum is over all isomorphism classes of abelian groups of order 2*n+1.`
	CROSSREFS	`Sequence in context: A099729 A123117 A062733 this_sequence A060635 A009478 A038057` `Adjacent sequences: A026736 A026737 A026738 this_sequence A026740 A026741 A026742`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Boddington (psb(AT)maths.warwick.ac.uk), Jan 26 2004`

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Last modified December 3 16:57 EST 2008. Contains 151279 sequences.

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