A090599 - OEIS

A090599

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

1, 4, 81, 16384, 48828125, 2821109907456, 3909821048582988049, 154742504910672534362390528, 202755595904452569706561330872953769, 10000000000000000000000000000000000000000000000

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OFFSET

1,2

COMMENTS

Also labeled commutative groupoids with an absorbant (zero) element.

LINKS

Table of n, a(n) for n=1..10.

Eric Postpischil Posting to sci.math newsgroup, May 21 1990

Eric Weisstein's World of Mathematics, Groupoid.

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: A068087 A324088 A357513 * A133396 A233001 A357781

Adjacent sequences: A090596 A090597 A090598 * A090600 A090601 A090602

KEYWORD

nonn

AUTHOR

Christian G. Bower, Dec 05 2003

STATUS

approved