A176142 Number of nonequivalent monoids of order n in which the action of the unit group on the maximal ideal is nontrivial.

0, 0, 0, 2, 5, 58, 428, 5539, 101082, 9269715

Offset

1,4

Comments

Monoids are considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).

The invertible elements form the unit group of the monoid, all remaining elements form the maximal ideal.

Links

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

A. Distler and T. W. Kelsey, The Monoids of Orders Eight, Nine & Ten, Annals of Mathematics and Artificial Intelligence, 56 (2009), 3-25.

Crossrefs

Cf. A058133, A151823

Sequence in context: A260654 A339167 A042161 * A101151 A138788 A030244

Adjacent sequences: A176139 A176140 A176141 * A176143 A176144 A176145

Keyword

hard,nonn

Author

Andreas Distler, Apr 10 2010

Status

approved