Number of regular semigroups of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).

A001427

Number of regular semigroups of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).

Terms

    a(0) =1a(1) =3a(2) =9a(3) =42a(4) =206a(5) =1352a(6) =10168a(7) =91073a(8) =925044

External references