%I A118099
%S A118099 1,3,8,24,76,284,1195
%N A118099 Number of inverse semigroups of order <= n.
%D A118099 M. V. Lawson, Inverse Semigroups: The Theory of Partial Symmetries. Singapore: 
               World Scientific, 1999.
%D A118099 E. S. Lyapin, Semigroups. Providence, RI: Amer. Math. Soc., 1974.
%D A118099 Weinstein, A. "Groupoids: Unifying Internal and External Symmetry." Not. 
               Amer. Math. Soc. 43, 744-752, 1996.
%H A118099 Eric Weisstein et al., <a href="http://mathworld.wolfram.com/InverseSemigroup.html">
               Inverse Semigroup.</a>
%H A118099 <a href="Sindx_Se.html#semigroups">Index entries for sequences related 
               to semigroups</a>.
%F A118099 a(n) = SUM[i=1..n] A001428(i).
%e A118099 a(7) = 1195 = 1 + 2 + 5 + 16 + 52 + 208 + 911.
%Y A118099 Partial sums of A001428.
%Y A118099 Sequence in context: A148782 A148783 A084205 this_sequence A066350 A148784 
               A148785
%Y A118099 Adjacent sequences: A118096 A118097 A118098 this_sequence A118100 A118101 
               A118102
%K A118099 nonn
%O A118099 1,2
%A A118099 Jonathan Vos Post (jvospost3(AT)gmail.com), May 11 2006