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A064341 Generalized Catalan numbers C(3,3; n). 1
1, 1, 6, 81, 1566, 36126, 921456, 25055001, 711951606, 20891575566, 628237506276, 19259213633226, 599654171202156, 18911332670183856, 602840023457208516, 19392890824608619401, 628769286622411762086 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

See triangle A064879 with columns m built from C(m,m; n), m >= 0, also for Derrida et al. and Liggett references.

LINKS

Table of n, a(n) for n=0..16.

FORMULA

a(n)= ((9^(n-1))/(n-1))*sum((m+1)*(m+2)*binomial(2*(n-2)-m, n-2-m)*((1/3)^(m+1)), m=0..n-2), n >= 2, a(0) := 1=: a(1).

G.f.:(1-5*x*c(9*x))/(1-3*x*c(9*x))^2 = c(9*x)*(5+4*c(9*x))/(1+2*c(9*x))^2 = (5*c(9*x)*(3*x)^2+4*(1+4*x))/(2+3*x)^2 with c(x)= A(x) g.f. of Catalan numbers A000108.

CROSSREFS

A064340.

Sequence in context: A196909 A197076 A234872 * A052756 A193265 A138457

Adjacent sequences:  A064338 A064339 A064340 * A064342 A064343 A064344

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang, Oct 12 2001

STATUS

approved

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Last modified December 20 21:43 EST 2014. Contains 252289 sequences.