%I A023814
%S A023814 1,1,8,113,3492,183732,17061118,7743056064
%N A023814 Number of associative binary operations on an n-set; number of labeled 
               semigroups.
%H A023814 Eric Postpischil <a href="http://groups.google.com/groups?&hl=en&lr=&ie=UTF-8&selm=11802%40shlump.nac.dec.com\
               &rnum=2">Posting to sci.math newsgroup, May 21 1990</a>
%H A023814 C. Noebauer, <a href="http://www.algebra.uni-linz.ac.at/~noebsi/">Home 
               page</a>
%H A023814 C. Noebauer, <a href="ftp://www.algebra.uni-linz.ac.at/pub/noebauer/smallrings.ps.gz">
               The Numbers of Small Rings</a>
%H A023814 C. Noebauer, <a href="ftp://www.algebra.uni-linz.ac.at/pub/noebauer/thesis.ps.gz">
               Thesis on the enumeration of near-rings</a>
%H A023814 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Semigroup.html">Link to a section of The World of Mathematics.</a>
%H A023814 <a href="Sindx_Se.html#semigroups">Index entries for sequences related 
               to semigroups</a>
%Y A023814 Cf. A001423, A001426, A023813, A023815, A027851.
%Y A023814 a(n)+A079172(n)=A002489(n)
%Y A023814 Sequence in context: A072402 A092084 A099715 this_sequence A062126 A113670 
               A156468
%Y A023814 Adjacent sequences: A023811 A023812 A023813 this_sequence A023815 A023816 
               A023817
%K A023814 nonn
%O A023814 0,3
%A A023814 Lyle Ramshaw (ramshaw(AT)pa.dec.com)