A058166 Triangle read by rows: T(n,k) = number of labeled semigroups of order n with k idempotents.

1, 4, 4, 24, 54, 35, 356, 1044, 1488, 604, 16585, 31620, 60900, 57900, 16727, 3461916, 1699290, 3345420, 4744380, 3128880, 681232, 6058301508, 265521354, 263429355, 439698420, 455785470, 222132666, 38187291

Offset: 1

Author

Christian G. Bower, Nov 15 2000

Keywords

• nonn
• tabl
• hard

Examples

			1; 4,4; 24,54,35; 356,1044,1488,604; ...
		

Links

• Index entries for sequences related to semigroups

Crossrefs

Row sums give A023814.