%I #6 Mar 30 2012 17:37:11
%S 1,1,1,2,6,19,68,285
%N Number of self-converse idempotent semigroups of order n.
%H <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a>
%Y Main diagonal of A058118.
%K nonn,hard
%O 0,4
%A _Christian G. Bower_, Nov 10 2000