Idempotent semigroups of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).
A002788
Idempotent 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) =1a(2) =2a(3) =6a(4) =26a(5) =135a(6) =875a(7) =6749a(8) =60601a(9) =618111a(10) =7033090
External references
- oeis: A002788