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A007853 Maximal antichains in rooted plane trees on n nodes. 1
1, 2, 5, 15, 50, 178, 663, 2553, 10086, 40669, 166752, 693331, 2917088, 12398545, 53164201, 229729439, 999460624, 4374546305, 19250233408, 85120272755, 378021050306, 1685406494673, 7541226435054, 33852474532769, 152415463629568 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..25.

R. Bacher, On generating series of complementary plane trees arXiv:math/0409050 [math.CO], 2004.

M. Klazar, Twelve countings with rooted plane trees, European Journal of Combinatorics 18 (1997), 195-210; Addendum, 18 (1997), 739-740.

Index entries for sequences related to rooted trees

FORMULA

G.f.: (1/4) * (3 - 2*x - sqrt(1-4*x) - sqrt(2) * sqrt((1+2*x) * sqrt(1-4*x) + 1 - 8*x + 2*x^2)) [from Klazar]. - Sean A. Irvine, Feb 06 2018

CROSSREFS

Sequence in context: A157135 A196836 A279553 * A149952 A060049 A107590

Adjacent sequences:  A007850 A007851 A007852 * A007854 A007855 A007856

KEYWORD

nonn

AUTHOR

Martin Klazar (klazar(AT)kam.mff.cuni.cz)

EXTENSIONS

More terms from Sean A. Irvine, Feb 06 2018

STATUS

approved

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Last modified February 25 14:46 EST 2018. Contains 299654 sequences. (Running on oeis4.)