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%I #8 Dec 31 2013 12:36:03
%S 1,2,5,16,51,201,877,4443,25284,161698,1145508,8910291,75373563,
%T 687950735,6727985390
%N Number of commutative inverse semigroups of order n.
%H Martin E. Malandro, <a href="http://arxiv.org/abs/1312.7192">Enumeration of finite inverse semigroups</a>, arXiv:1312.7192 [math.CO]
%Y Cf. A001428 (inverse semigroups), A234844 (inverse monoids), A234845 (commutative inverse monoids).
%K nonn,hard,more
%O 1,2
%A _Joerg Arndt_, Dec 31 2013