%I #15 Jan 23 2022 18:26:46
%S 0,1,4,243,1048576,762939453125,170581728179578208256,
%T 18562115921017574302453163671207,
%U 1427247692705959881058285969449495136382746624,106111661199647248543687855752712667991103904330482569981872649
%N Number of n-element labeled groupoids with an identity.
%C Also labeled groupoids with an absorbant (zero) element.
%H Andrew Howroyd, <a href="/A090602/b090602.txt">Table of n, a(n) for n = 0..20</a>
%H Eric Postpischil <a href="http://groups.google.com/groups?&hl=en&lr=&ie=UTF-8&selm=11802%40shlump.nac.dec.com&rnum=2">Posting to sci.math newsgroup, May 21 1990</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Groupoid.html">Groupoid</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Magma_(algebra)">Magma (algebra)</a>
%H <a href="/index/Gre#groupoids">Index entries for sequences related to groupoids</a>
%F a(n) = n^((n-1)^2+1).
%F a(n) = A090603(n)*n.
%o (PARI) a(n) = n^((n-1)^2+1) \\ _Andrew Howroyd_, Jan 23 2022
%Y Cf. A090601 (isomorphism classes), A090603.
%K nonn
%O 0,3
%A _Christian G. Bower_, Dec 05 2003
%E a(0)=0 prepended and a(9) added by _Andrew Howroyd_, Jan 23 2022