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A304068 Number of trees on n vertices rooted at an oriented non-edge. 2
0, 0, 1, 4, 14, 45, 140, 424, 1269, 3760, 11080, 32517, 95190, 278154, 811887, 2367973, 6903453, 20120905, 58639016, 170894228, 498084608, 1451899005, 4232957241, 12343454790, 36001675800, 105028397290, 306472665459, 894497511566 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..28.

FORMULA

A000106(n) + a(n) = A000243(n).

EXAMPLE

a(4)=4 is based on the same examples as in A304067, but the oriented edge that spans a leaf with the node at distance 2 in the linear graph may have 2 orientations, so a(4) is one larger than A304067(4).

CROSSREFS

Cf. A000055 (not rooted), A000106 (rooted at oriented edge)

Sequence in context: A318019 A182902 A108765 * A005775 A094688 A068092

Adjacent sequences:  A304065 A304066 A304067 * A304069 A304070 A304071

KEYWORD

nonn

AUTHOR

Brendan McKay, May 05 2018

STATUS

approved

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Last modified December 15 00:30 EST 2019. Contains 329988 sequences. (Running on oeis4.)