A193487 - OEIS

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A193487

Number of rooted trees with n nodes and omega-valency 2.

5

0, 0, 0, 1, 1, 5, 9, 29, 62, 181, 422, 1166, 2885, 7788, 19893, 53319, 138931, 372027, 982379, 2635898, 7026483, 18914903, 50781803, 137201419, 370442111, 1004512375, 2724867782, 7414635185, 20193165834, 55125632502

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

OFFSET

1,6

COMMENTS

See A003120 for definitions.

LINKS

Table of n, a(n) for n=1..30.

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

CROSSREFS

Cf. A003120, A193488, A193489, A193490, A193491.

Sequence in context: A163779 A280487 A191013 * A006131 A352008 A270595

Adjacent sequences: A193484 A193485 A193486 * A193488 A193489 A193490

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jul 27 2011

STATUS

approved