Irregular triangle read by rows: T(n,k) is the number of labeled relations on n nodes with exactly k edges; n>=0, 0<=k<=n^2.

A217285

Irregular triangle read by rows: T(n,k) is the number of labeled relations on n nodes with exactly k edges; n>=0, 0<=k<=n^2.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =4a(5) =6a(6) =4a(7) =1a(8) =1a(9) =9a(10) =36a(11) =84a(12) =126a(13) =126a(14) =84a(15) =36a(16) =9a(17) =1a(18) =1a(19) =16a(20) =120a(21) =560a(22) =1820a(23) =4368a(24) =8008a(25) =11440a(26) =12870a(27) =11440a(28) =8008a(29) =4368

External references