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%I #12 Feb 02 2023 15:07:31
%S 0,0,54,12664
%N Number of nonisomorphic groupoids with 1 idempotent and a nontrivial symmetry.
%H <a href="/index/Gre#groupoids">Index entries for sequences related to groupoids</a>
%F a(n) = A030253(n) - A030271(n).
%Y Column k=1 of A038020.
%Y Cf. A030253, A030271.
%K nonn,more
%O 1,3
%A _Christian G. Bower_
%E a(3) corrected by _Andrew Howroyd_, Feb 02 2023