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%I #19 Oct 27 2019 14:27:46
%S 0,1,2,6,27,156,1373,17730,858977,1844075697,52991253973742
%N Number of monoids (semigroups with identity) of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).
%H Eric Postpischil <a href="https://groups.google.com/d/msg/sci.math/nU-hg-FFSFo/iIB3Lul1sAEJ">Posting to sci.math newsgroup, May 21 1990</a>
%H Andreas Distler and Tom Kelsey, <a href="https://doi.org/10.1007/978-3-540-85110-3_7">The Monoids of Order Eight and Nine</a>. Lecture Notes in Computer Science 5144 (2008), 61-76.
%H Andreas Distler and Tom Kelsey, <a href="https://doi.org/10.1007/s10472-009-9140-y">The Monoids of Orders Eight, Nine & Ten</a>. Annals of Mathematics and Artificial Intelligence 56 (2009), 3-25.
%H <a href="/index/Mo#monoids">Index entries for sequences related to monoids</a>
%F a(n)=(A058129(n)+A058132(n))/2.
%Y Cf. A001423, A058129, A058132, A151823.
%K nonn,more,hard
%O 0,3
%A _Christian G. Bower_, Nov 13 2000
%E a(8) and a(9) from Distler & Kelsey (2008), added by _N. J. A. Sloane_, Jul 10 2009
%E a(10) from Distler & Kelsey (2009), added by _Max Alekseyev_, Jul 13 2009
%E a(0) prepended by _Jianing Song_, Oct 26 2019
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