Triangular array read by rows. T(n,k) is the number of digraphs with n labeled nodes having exactly k undirected (or weak) components, n >= 1, 1 <= k <= n.

A189898

Triangular array read by rows. T(n,k) is the number of digraphs with n labeled nodes having exactly k undirected (or weak) components, n >= 1, 1 <= k <= n.

Terms

    a(0) =1a(1) =3a(2) =1a(3) =54a(4) =9a(5) =1a(6) =3834a(7) =243a(8) =18a(9) =1a(10) =1027080a(11) =20790a(12) =675a(13) =30a(14) =1a(15) =1067308488a(16) =6364170a(17) =67635a(18) =1485a(19) =45a(20) =1a(22) =7543111716a(23) =23031540a(24) =171045a(25) =2835a(26) =63a(27) =1a(30) =30469951764a(31) =63580545a(32) =370440

External references