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
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
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