A058105 Number of commutative asymmetric semigroups of order n.

1, 1, 3, 9, 39, 201, 1258, 10013, 142755

Offset

0,3

Links

Table of n, a(n) for n=0..8.

Index entries for sequences related to semigroups

Formula

a(n) = A079201(n, A027423(n)).

Crossrefs

Cf. A001426, A079201.

Sequence in context: A130905 A030799 A273396 * A090012 A340913 A079096

Adjacent sequences: A058102 A058103 A058104 * A058106 A058107 A058108

Keyword

nonn,hard

Author

Christian G. Bower, Nov 09 2000

Extensions

Updated Feb 19 2001.

a(7) corrected Dec 26 2006

a(8) from Andrew Howroyd, Jan 26 2022

Status

approved