A058147 Triangle read by rows: number of monoids of order n with k idempotents, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).
1, 1, 1, 1, 3, 2, 2, 9, 10, 6, 1, 30, 47, 52, 26, 2, 175, 283, 413, 365, 135, 1, 3333, 2139, 3630, 4597, 3155, 875, 5
Offset: 1
Examples
1; 1,1; 1,3,2; 2,9,10,6; 1,30,47,52,26; ...