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%I #10 Jan 23 2022 20:03:37
%S 1,1,8,5832,764411904,32000000000000000,669462604992000000000000000,
%T 10090701947420325348336258984797490118656,
%U 149274165541848061518941637595308945760198454444667437056,2832386113499265897149023834314938475799908379160975581551362823935905234944
%N Number of anti-commutative closed binary operations (groupoids) on a set of order n.
%H Andrew Howroyd, <a href="/A079189/b079189.txt">Table of n, a(n) for n = 0..20</a>
%H C. van den Bosch, <a href="http://cosmos.ucc.ie/~cjvdb1/html/binops.shtml">Closed binary operations on small sets</a>
%H <a href="/index/Gre#groupoids">Index entries for sequences related to groupoids</a>
%F a(n) = (n^n)*((n^2-n)^((n^2-n)/2)).
%F a(n) = A002489(n) - A079186(n).
%F a(n) = Sum_{k>=1} A079191(n,k)*A079210(n,k).
%F a(n) = A023813(n)*A023813(n-1).
%o (PARI) a(n) = (n^n)*((n^2-n)^((n^2-n)/2)) \\ _Andrew Howroyd_, Jan 23 2022
%Y Cf. A023813, A079186, A079190 (isomorphism classes), A079191, A079210.
%K nonn
%O 0,3
%A Christian van den Bosch (cjb(AT)cjb.ie), Jan 03 2003
%E Edited and extended by _Christian G. Bower_, Dec 12 2003
%E a(0)=1 prepended, a(8) corrected and a(9) added by _Andrew Howroyd_, Jan 23 2022
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