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A036362 Number of labeled 3-trees with n nodes. 8
0, 0, 1, 1, 10, 200, 5915, 229376, 10946964, 618435840, 40283203125, 2968444272640, 243926836708126, 22100985366992896, 2187905889450121295, 234881024000000000000, 27172548942138551952680, 3369317755618569294053376, 445726953911853022186520169 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

REFERENCES

F. Harary and E. Palmer, Graphical Enumeration, (1973), p. 30, Problem 1.13(b) with k=3.

LINKS

T. D. Noe, Table of n, a(n) for n=1..100

Index entries for sequences related to trees

FORMULA

C(n, 3)*(3*n-8)^(n-5).

Number of labeled k-trees on n nodes is binomial(n, k) * (k(n-k)+1)^(n-k-2).

MAPLE

[ seq(binomial(n, 3)*(3*n-8)^(n-5), n=1..20) ];

CROSSREFS

Cf. A000272, A036361.

Cf. A000272 (labeled trees), A036361 (labeled 2-trees), A036362 (labeled 3-trees), A036506 (labeled 4-trees), A000055 (unlabeled trees), A054581 (unlabeled 2-trees).

Sequence in context: A202436 A237025 A156275 * A051262 A178020 A279833

Adjacent sequences:  A036359 A036360 A036361 * A036363 A036364 A036365

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified February 22 03:55 EST 2018. Contains 299428 sequences. (Running on oeis4.)