Number of semigroups of order n with 2 idempotents, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).
A002787
Number of semigroups of order n with 2 idempotents, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).
Terms
- a(0) =2a(1) =7a(2) =37a(3) =216a(4) =1780a(5) =32652a(6) =4665709a(7) =12710266442
External references
- oeis: A002787