A058105 - OEIS

%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