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%I #4 Jan 02 2019 14:58:29
%S 0,1,2,9,30,213,1757,22956,955569,1853259264
%N Number of nonequivalent monoids of order n with more than one invertible element
%C a(n) is also the number of nonequivalent monoids with nontrivial unit group. [From Tom Kelsey (tom(AT)cs.st-and.ac.uk), Apr 01 2010]
%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>, in: Intelligent Computer Mathematics, Lecture Notes in Computer Science, Volume 5144/2008, pp. 61-76, Springer-Verlag.
%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. [From Tom Kelsey (tom(AT)cs.st-and.ac.uk), Apr 01 2010]
%Y Cf. A001423, A058133.
%K nonn
%O 1,3
%A _N. J. A. Sloane_, Jul 10 2009
%E Definition corrected by Tom Kelsey (tom(AT)cs.st-andrews.ac.uk), Apr 01 2010
%E Corrected and extended by Tom Kelsey (tom(AT)cs.st-and.ac.uk), Apr 01 2010
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