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Number of isomorphism classes of non-commutative closed binary operations (groupoids) on a set of order n.
4

%I #8 Mar 30 2012 17:37:12

%S 0,6,3201,178937984,2483527282664925,14325590003288422852104768,

%T 50976900301814583996024242298024434780,

%U 155682086691137947272042494203068030678979503481450216

%N Number of isomorphism classes of non-commutative closed binary operations (groupoids) on a set of order n.

%C A001425(n)+a(n)=A001329(n).

%C Each a(n) is equal to the sum of the elements in row n of A079184.

%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>

%K nonn

%O 1,2

%A Christian van den Bosch (cjb(AT)cjb.ie), Jan 03 2003

%E Edited and extended by _Christian G. Bower_, Dec 12 2003