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A045738 Branches in all noncrossing rooted trees on n nodes on a circle. 1
1, 4, 24, 148, 925, 5838, 37128, 237576, 1527867, 9867000, 63946740, 415683216, 2709186844, 17697136408, 115833872400, 759517409424, 4987999112007, 32804320226580, 216018805979760, 1424151150922500, 9398957079664845, 62090203617715350, 410536632908307360 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Table of n, a(n) for n=2..24.

Index entries for sequences related to rooted trees

FORMULA

a(n) = binomial(3n-3, n-2) - 2*binomial(3n-6, n-3).

G.f.: (2*g^3-4*g^2+2*g-1)/((1-3*g)*(g-1)^3) where g*(1-g)^2 = x. - Mark van Hoeij, Nov 10 2011

CROSSREFS

Sequence in context: A072949 A104531 A225050 * A215708 A192806 A192927

Adjacent sequences:  A045735 A045736 A045737 * A045739 A045740 A045741

KEYWORD

nonn

AUTHOR

Emeric Deutsch

STATUS

approved

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Last modified June 17 23:56 EDT 2013. Contains 226327 sequences.