Triangle read by rows: T(n,k) is the number of isomorphism classes of commutative semigroups of order n with k idempotents.
A058116
Triangle read by rows: T(n,k) is the number of isomorphism classes of commutative semigroups of order n with k idempotents.
Terms
- a(0) =1a(1) =2a(2) =1a(3) =5a(4) =5a(5) =2a(6) =16a(7) =23a(8) =14a(9) =5a(10) =62a(11) =106a(12) =93a(13) =49a(14) =15a(15) =342a(16) =544a(17) =582a(18) =422a(19) =200a(20) =53a(21) =3435a(22) =3380a(23) =3773a(24) =3360a(25) =2178a(26) =943a(27) =222a(28) =97061a(29) =30788
External references
- oeis: A058116