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A350610 Irregular triangle read by rows: T(n,k) (n >= 1, 0 <= k <= (n-1)*(n-2)/2) = number of weakly connected subdigraphs of the transitive tournament on n nodes that have k arcs. 3
1, 1, 1, 3, 1, 6, 15, 9, 1, 10, 45, 120, 162, 109, 27, 1, 15, 105, 455, 1365, 2755, 3738, 3353, 1889, 600, 81, 1, 21, 210, 1330, 5985, 20349, 52764, 104726, 159351, 185155, 162455, 105436, 48881, 15255, 2862, 243, 1, 28, 378, 3276, 20475, 98280, 376740, 1173564, 2995480, 6295857, 10925190, 15658609, 18498220, 17926289, 14138445, 8968823, 4498534, 1740117, 499834, 100225, 12501, 729 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

The sum of row n is A350608(n).

For references and links see A350608.

LINKS

Don Knuth, Rows n = 1..16, flattened

Don Knuth, The first 16 rows.

EXAMPLE

For example, when n=4, the 31 weakly connected graphs have respectively 1, 6, 15, 9 cases with 0, 1, 2, and 3 arcs (as in the example given for A350608).

Triangle T(n,k) begins:

  1;

  1;

  1,  3;

  1,  6,  15,   9;

  1, 10,  45, 120,  162,  109,   27;

  1, 15, 105, 455, 1365, 2755, 3738, 3353, 1889, 600, 81;

  ...

CROSSREFS

Cf. A350608, A350609.

Sequence in context: A193091 A049966 A187120 * A140982 A100232 A221937

Adjacent sequences:  A350607 A350608 A350609 * A350611 A350612 A350613

KEYWORD

nonn,tabf

AUTHOR

Don Knuth, Jan 16 2022

STATUS

approved

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Last modified October 4 09:28 EDT 2022. Contains 357239 sequences. (Running on oeis4.)