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A023422 Generalized Catalan Numbers. 5

%I

%S 1,1,1,1,1,1,2,4,8,16,32,64,129,261,530,1080,2208,4528,9313,19207,

%T 39714,82314,170996,355976,742545,1551817,3248823,6812947,14309557,

%U 30099645,63402315

%N Generalized Catalan Numbers.

%H Seiichi Manyama, <a href="/A023422/b023422.txt">Table of n, a(n) for n = 0..2926</a>

%H A. Goupil, M.-E. Pellerin and J. de Wouters d'oplinter, <a href="http://arxiv.org/abs/1307.8432">Snake Polyominoes</a>, arXiv preprint arXiv:1307.8432, 2013. (Gives a g.f.)

%t a[0]=1; a[n_]:= a[n]=a[n-1] + Sum[a[k]*a[n-2-k], {k,4,n-2}]; Table[a[n], {n,0,30}] (* modified by _G. C. Greubel_, Jan 01 2018 *)

%o (PARI) {a(n) = if(n==0,1, a(n-1) + sum(k=4,n-2, a(k)*a(n-k-2)))};

%o for(n=0,30, print1(a(n), ", ")) \\ _G. C. Greubel_, Jan 01 2018

%Y Cf. A000108, A001006, A004148, A004149, A023421, A023423.

%Y Fifth row of A064645.

%K nonn,easy

%O 0,7

%A _Olivier GĂ©rard_

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Last modified October 16 21:57 EDT 2018. Contains 316275 sequences. (Running on oeis4.)