id:A090599 - OEIS Search Results

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Number of n-element labeled commutative groupoids with an identity.

+0
2

1, 4, 81, 16384, 48828125, 2821109907456, 3909821048582988049, 154742504910672534362390528, 202755595904452569706561330872953769, 10000000000000000000000000000000000000000000000 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also labeled commutative groupoids with an absorbant (zero) element.`
	LINKS	`Eric Postpischil Posting to sci.math newsgroup, May 21 1990` `Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.` `Index entries for sequences related to groupoids`
	FORMULA	`a(n) = n^(1+binomial(n, 2))`
	CROSSREFS	`a(n) = A076113(n)*n. Cf. A038017.` `Sequence in context: A123198 A128911 A068087 this_sequence A133396 A007154 A056410` `Adjacent sequences: A090596 A090597 A090598 this_sequence A090600 A090601 A090602`
	KEYWORD	`nonn`
	AUTHOR	`Christian G. Bower (bowerc(AT)usa.net), Dec 05 2003`

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Last modified July 24 12:00 EDT 2008. Contains 142294 sequences.

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