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%I #4 Sep 21 2017 09:03:21
%S 1,0,0,58,6634,0
%N Number of centrist groupoids with n elements.
%C Systems with a binary operation that satisfies AB.BA=B. The rule is anti-commutative. Any central groupoid is centrist.
%C For comparison, a central groupoid is a system with a binary operator that satisfies the equation AB.BC=B (or (AB)(BC)=B). These have the curious property that the finite systems have a square number of elements. What is the beginning of the sequence giving the number of central groupoids of order n^2?
%K nonn,more
%O 1,4
%A _N. J. A. Sloane_, Apr 28 2007, based on email from Richard C. Schroeppel (rcs(AT)CS.Arizona.EDU), Mar 15 2007.