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A132835 Largest terms a(n) forming a self-convolution cube of an integer sequence (A132836) such that: a(n) <= 3*a(n-1) for n>0 with a(0)=1. 4

%I #2 Mar 30 2012 18:37:04

%S 1,3,9,25,75,225,674,2022,6066,18196,54588,163764,491291,1473873,

%T 4421619,13264856,39794568,119383704,358151111,1074453333,3223359999,

%U 9670079995,29010239985,87030719955,261092159865,783276479595

%N Largest terms a(n) forming a self-convolution cube of an integer sequence (A132836) such that: a(n) <= 3*a(n-1) for n>0 with a(0)=1.

%o (PARI) {a(n)=local(B=[1],R);if(n==0,1,for(k=1,n,t=3*a(k-1);B=concat(B,t); R=Vec(Ser(B)^(1/3))[ #B]; B[ #B]=t-(numerator(R)%3)*(denominator(R)-1)/2 ));B[n+1]}

%Y Cf. A132836 (cube-root); A132831 (variant).

%K nonn

%O 0,2

%A _Paul D. Hanna_, Sep 07 2007

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