Triangle read by rows: number of nonisomorphic semigroups of order n with k idempotents.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =9a(5) =10a(6) =20a(7) =50a(8) =72a(9) =46a(10) =171a(11) =309a(12) =590a(13) =594a(14) =251a(15) =5284a(16) =2806a(17) =5422a(18) =7772a(19) =5668a(20) =1682a(21) =1224331a(22) =58583a(23) =61323a(24) =101539a(25) =109107a(26) =59576a(27) =13213a(28) =3667785000a(29) =9207430