A151823 Number of nonequivalent monoids of order n with more than one invertible element

0, 1, 2, 9, 30, 213, 1757, 22956, 955569, 1853259264

Offset

1,3

Comments

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]

Links

Table of n, a(n) for n=1..10.

Andreas Distler and Tom Kelsey, The Monoids of Order Eight and Nine, in: Intelligent Computer Mathematics, Lecture Notes in Computer Science, Volume 5144/2008, pp. 61-76, Springer-Verlag.

Andreas Distler and Tom Kelsey, The Monoids of Orders Eight, Nine & Ten, Annals of Mathematics and Artificial Intelligence, 56 (2009), 3-25. [From Tom Kelsey (tom(AT)cs.st-and.ac.uk), Apr 01 2010]

Crossrefs

Cf. A001423, A058133.

Sequence in context: A318101 A358652 A347893 * A084652 A188776 A261443

Adjacent sequences: A151820 A151821 A151822 * A151824 A151825 A151826

Keyword

nonn

Author

N. J. A. Sloane, Jul 10 2009

Extensions

Definition corrected by Tom Kelsey (tom(AT)cs.st-andrews.ac.uk), Apr 01 2010

Corrected and extended by Tom Kelsey (tom(AT)cs.st-and.ac.uk), Apr 01 2010

Status

approved