A090602 Number of n-element labeled groupoids with an identity.

0, 1, 4, 243, 1048576, 762939453125, 170581728179578208256, 18562115921017574302453163671207, 1427247692705959881058285969449495136382746624, 106111661199647248543687855752712667991103904330482569981872649

Offset

0,3

Comments

Also labeled groupoids with an absorbant (zero) element.

Links

Andrew Howroyd, Table of n, a(n) for n = 0..20

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

Eric Weisstein's World of Mathematics, Groupoid

Wikipedia, Magma (algebra)

Index entries for sequences related to groupoids

Formula

a(n) = n^((n-1)^2+1).

a(n) = A090603(n)*n.

Prog

(PARI) a(n) = n^((n-1)^2+1) \\ Andrew Howroyd, Jan 23 2022

Crossrefs

Cf. A090601 (isomorphism classes), A090603.

Sequence in context: A091792 A300595 A320418 * A180722 A087587 A346919

Adjacent sequences: A090599 A090600 A090601 * A090603 A090604 A090605

Keyword

nonn

Author

Christian G. Bower, Dec 05 2003

Extensions

a(0)=0 prepended and a(9) added by Andrew Howroyd, Jan 23 2022

Status

approved