Triangle read by rows: T(n,k) is number of labeled bipartite graphs with n nodes and k edges.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =3a(6) =3a(7) =1a(8) =6a(9) =15a(10) =16a(11) =3a(12) =1a(13) =10a(14) =45a(15) =110a(16) =140a(17) =60a(18) =10a(19) =1a(20) =15a(21) =105a(22) =435a(23) =1125a(24) =1701a(25) =1200a(26) =480a(27) =105a(28) =10a(29) =1