OFFSET
0,2
COMMENTS
In Blieberger and Kirschenhofer 2014 denoted by r_n on page 106 equation (5).
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..80
J. Blieberger and P. Kirschenhofer, Generalized Catalan Sequences Originating from the Analysis of Special Data Structures, Bulletin of the ICA, 71 (2014) 103-116.
FORMULA
a(n) ~ 2^((n^2 + 3*n)/2) * c where c = 0.7153374336... .
PROG
(PARI) {a(n) = if( n<1, n==0, 2^n * sum(k=0, n-1, a(k) * a(n-1-k)))};
(Haskell)
a254744 n = a254744_list !! n
a254744_list = 1 : f 2 [1] where
f x ys = y : f (x * 2) (y : ys) where
y = x * (sum $ zipWith (*) ys $ reverse ys)
-- Reinhard Zumkeller, Feb 07 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael Somos, Feb 06 2015
STATUS
approved