Number of labeled semigroups with n elements and empty center.
A391158
Number of labeled semigroups with n elements and empty center.
Terms
- a(0) =1a(1) =0a(2) =2a(3) =26a(4) =944a(5) =53242a(6) =4645942a(7) =605080534
External references
- oeis: A391158