Triangle read by rows: monoids of order n with k idempotents.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =3a(6) =2a(7) =9a(8) =14a(9) =10a(10) =1a(11) =32a(12) =63a(13) =86a(14) =46a(15) =2a(16) =219a(17) =406a(18) =694a(19) =665a(20) =251a(21) =1a(22) =5585a(23) =3331a(24) =6343a(25) =8582a(26) =6035a(27) =1682a(28) =5