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

A391157

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

Terms

    a(0) =1a(1) =0a(2) =1a(3) =2a(4) =0a(5) =6a(6) =26a(7) =24a(8) =0a(9) =63a(10) =944a(11) =664a(12) =744a(13) =0a(14) =1140a(15) =53242a(16) =35780a(17) =32480a(18) =31500a(19) =0a(20) =30730a(21) =4645942a(22) =2823984a(23) =3482160a(24) =3014160a(25) =1909800a(26) =0a(27) =1185072a(28) =605080534a(29) =317296420

External references