Triangle read by rows: T(n,k) is the number of nonisomorphic semigroups with n elements whose center contains k elements.

A391159

Triangle read by rows: T(n,k) is the number of nonisomorphic semigroups with n elements whose center contains k elements.

Terms

    a(0) =1a(1) =0a(2) =1a(3) =2a(4) =0a(5) =3a(6) =6a(7) =6a(8) =0a(9) =12a(10) =55a(11) =35a(12) =40a(13) =0a(14) =58a(15) =552a(16) =387a(17) =326a(18) =325a(19) =0a(20) =325a(21) =7954a(22) =4849a(23) =5739a(24) =4770a(25) =3179a(26) =0a(27) =2143a(28) =143958a(29) =77299

External references