%I #18 Sep 03 2024 08:24:54
%S 1,0,2,52,421560
%N Number of anti-associative closed binary operations on a set of order n.
%H Christian van den Bosch, <a href="https://web.archive.org/web/20071014230143/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) = A002489(n) - A079176(n).
%F a(n) = Sum_{k>=1} A079181(n,k)*A079210(n,k).
%Y Cf. A079176, A079180 (isomorphism classes), A079181, A079210.
%K nonn,more
%O 0,3
%A Christian van den Bosch (cjb(AT)cjb.ie), Jan 03 2003
%E a(0)=1 prepended and a(1) corrected by _Kamil Zabielski_, Aug 28 2024