Triangle T(n,k) of number of digraphs with a source on n unlabeled nodes with k arcs, k=0..n*(n-1).

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =0a(5) =0a(6) =2a(7) =4a(8) =4a(9) =1a(10) =1a(11) =0a(12) =0a(13) =0a(14) =4a(15) =16a(16) =34a(17) =46a(18) =38a(19) =27a(20) =13a(21) =5a(22) =1a(23) =1a(24) =0a(25) =0a(26) =0a(27) =0a(28) =9a(29) =56