A193491 - OEIS

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A193491

Irregular triangle read by rows: row n gives numbers of rooted trees with n nodes (n >= 1) and omega-valency k (k >= 1).

1, 1, 2, 3, 1, 7, 1, 1, 13, 5, 1, 1, 31, 9, 6, 1, 1, 66, 29, 11, 7, 1, 1, 159, 62, 42, 13, 8, 1, 1, 365, 181, 92, 55, 15, 9, 1, 1, 900, 422, 294, 127, 70, 17, 10, 1, 1, 2162, 1166, 720, 435, 165, 86, 19, 11, 1, 1, 5417, 2885, 2119, 1110, 608, 208, 104, 21, 12, 1, 1

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OFFSET

1,3

COMMENTS

See A003120 for definitions.

LINKS

Table of n, a(n) for n=1..68.

J.-C. Arditti, Dénombrement des arborescences dont le graphe de comparabilité est Hamiltonien, Discrete Math., 5 (1973), 189-200.

EXAMPLE

Triangle begins:

3, 1

7, 1, 1