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A036363 Line-labeled 2-trees with n nodes. 0
1, 30, 2940, 612360, 221371920, 123506903520, 98513415000000, 106466143825641600, 149822417112092524800, 266259578976734741798400, 583256031964344606759091200, 1544112027465820312500000000000, 4860420955731492909364541975040000 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

REFERENCES

F. Harary and E. Palmer, Graphical Enumeration, (1973), p. 30, Problem 1.13(c).

LINKS

Table of n, a(n) for n=3..15.

Index entries for sequences related to trees

MAPLE

[ seq((2*n-3)!*(2*n-3)^(n-4)/(2*(n-2)!), n=3..20) ];

CROSSREFS

Sequence in context: A091544 A230728 A108091 * A230591 A001459 A303007

Adjacent sequences:  A036360 A036361 A036362 * A036364 A036365 A036366

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified November 20 15:12 EST 2018. Contains 317402 sequences. (Running on oeis4.)