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%I #18 Oct 27 2019 14:28:46
%S 1,0,3,17,153,1687,26397,1596113,3682361420
%N Number of semigroups of order n without identity.
%H <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a>
%F a(n) = A027851(n) - A058129(n).
%Y Cf. A027851, A058129.
%K nonn,more
%O 0,3
%A _Steve Szabo_, Sep 06 2018
%E More terms from _Joerg Arndt_, Dec 09 2018
%E a(0) prepended by _Jianing Song_, Oct 26 2019
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