A090599 Number of n-element labeled commutative groupoids with an identity.

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

Offset: 1

Author

Christian G. Bower, Dec 05 2003

Keywords

• nonn

Comments

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, Groupoid.
• Index entries for sequences related to groupoids

Crossrefs

a(n) = A076113(n)*n. Cf. A038017.

Formula

a(n) = n^(1+binomial(n, 2))