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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. 5
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 16 21:38 EDT 2022. Contains 356169 sequences. (Running on oeis4.)