A350491 Triangle read by rows: T(n,k) is the number of acyclic digraphs on n unlabeled nodes with k arcs and a global source and sink, n >= 1, k = 0..n*(n-1)/2.

1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 4, 4, 1, 0, 0, 0, 0, 1, 9, 25, 32, 22, 8, 1, 0, 0, 0, 0, 0, 1, 17, 92, 259, 441, 496, 379, 195, 66, 13, 1, 0, 0, 0, 0, 0, 0, 1, 28, 259, 1286, 4026, 8754, 13930, 16686, 15289, 10785, 5842, 2397, 722, 151, 19, 1

Offset

1,12

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, 1, 1;
  [4] 0, 0, 0, 1, 4, 4,  1;
  [5] 0, 0, 0, 0, 1, 9, 25, 32,  22,   8,   1;
  [6] 0, 0, 0, 0, 0, 1, 17, 92, 259, 441, 496, 379, 195, 66, 13, 1;
  ...

Prog

(PARI) \\ See PARI link in A122078 for program code.
{ my(A=A350491rows(7)); for(i=1, #A, print(A[i])) }

Crossrefs

Row sums are A345258.

Column sums are A350492.

Cf. A122078, A350447, A350449, A350488.

Sequence in context: A204384 A102412 A372005 * A365957 A365954 A260043

Adjacent sequences: A350488 A350489 A350490 * A350492 A350493 A350494

Keyword

nonn,tabf

Author

Andrew Howroyd, Jan 08 2022

Status

approved