A058105 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A058105

Number of commutative asymmetric semigroups of order n.

%I #12 Jan 26 2022 14:20:13

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

%N Number of commutative asymmetric semigroups of order n.

%H <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a>

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

%Y Cf. A001426, A079201.

%K nonn,hard

%O 0,3

%A _Christian G. Bower_, Nov 09 2000

%E Updated Feb 19 2001.

%E a(7) corrected Dec 26 2006

%E a(8) from _Andrew Howroyd_, Jan 26 2022