A350753 Triangle read by rows: T(n,k) is the number of unlabeled strongly connected digraphs with n arcs and k vertices, n >= 0, k = 1..n+1.

1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 2, 1, 0, 0, 0, 1, 4, 1, 0, 0, 0, 1, 16, 7, 1, 0, 0, 0, 0, 22, 58, 10, 1, 0, 0, 0, 0, 22, 240, 165, 14, 1, 0, 0, 0, 0, 11, 565, 1281, 365, 18, 1, 0, 0, 0, 0, 5, 928, 6063, 4838, 733, 23, 1, 0, 0, 0, 0, 1, 1065, 19591, 38516, 14661, 1317, 28, 1, 0

Offset: 0

Author

Andrew Howroyd, Jan 14 2022

Keywords

• nonn
• tabl

Examples

			Triangle begins:
  1;
  0, 0;
  0, 1, 0;
  0, 0, 1,  0;
  0, 0, 2,  1,   0;
  0, 0, 1,  4,   1,    0;
  0, 0, 1, 16,   7,    1,   0;
  0, 0, 0, 22,  58,   10,   1,  0;
  0, 0, 0, 22, 240,  165,  14,  1, 0;
  0, 0, 0, 11, 565, 1281, 365, 18, 1, 0;
		

Crossrefs

Row sums are A350752.

Column sums are A035512.

Cf. A057276 (transpose), A350450, A350489.

Programs

PARI

\\ See PARI link in A350489 for program code.
my(A=A350753rows(10)); for(n=1, #A, print(A[n]))