A350488 Triangle read by rows: T(n,k) is the number of acyclic digraphs on n unlabeled nodes with k arcs and a global source, n >= 1, k = 0..n*(n-1)/2.

1, 0, 1, 0, 0, 2, 1, 0, 0, 0, 4, 6, 5, 1, 0, 0, 0, 0, 9, 25, 47, 46, 27, 9, 1, 0, 0, 0, 0, 0, 20, 95, 297, 582, 783, 738, 501, 235, 75, 14, 1, 0, 0, 0, 0, 0, 0, 48, 337, 1575, 4941, 11295, 19404, 25847, 26966, 22195, 14380, 7280, 2831, 816, 165, 20, 1

Offset

1,6

Links

Andrew Howroyd, Table of n, a(n) for n = 1..1350 (rows 1..20)

Example

Triangle begins:
  [1] 1;
  [2] 0, 1;
  [3] 0, 0, 2, 1;
  [4] 0, 0, 0, 4, 6,  5,  1;
  [5] 0, 0, 0, 0, 9, 25, 47, 46, 27, 9, 1;
  [6] 0, 0, 0, 0, 0, 20, 95, 297, 582, 783, 738, 501, 235, 75, 14, 1;
  ...

Prog

(PARI) \\ See PARI link in A122078 for program code.
{ my(A=A350488rows(7)); for(i=1, #A, print(A[i])) }

Crossrefs

Row sums are A350415.

Column sums are A350490.

Leading diagonal is A000081.

The labeled version is A350487.

Cf. A122078, A350447, A350449, A350491.

Sequence in context: A326453 A130116 A325774 * A212868 A184616 A261139

Adjacent sequences: A350485 A350486 A350487 * A350489 A350490 A350491

Keyword

nonn,tabf

Author

Andrew Howroyd, Jan 01 2022

Status

approved