%I #4 Mar 14 2015 12:04:55
%S 1,4,14,56,221,884,3534,14136,56542,226168,904672,3618688,14474751,
%T 57899004,231596014,926384056,3705536222,14822144888,59288579552,
%U 237154318208,948617272832,3794469091328,15177876365312,60711505461248
%N Largest terms a(n) forming a self-convolution 4th power of an integer sequence (A132838) such that: a(n) <= 4*a(n-1) for n>0 with a(0)=1.
%o (PARI) {a(n)=local(A,t,r=1);A=if(n==0,[1],vector(n,j,a(j-1)));if(n==0,r=1,t=a(n-1); if(denominator(Vec(Ser(concat(A,4*t))^(1/4))[n+1])==1,r=4*t, if(denominator(Vec(Ser(concat(A,4*t-1))^(1/4))[n+1])==1,r=4*t-1, if(denominator(Vec(Ser(concat(A,4*t-2))^(1/4))[n+1])==1,r=4*t-2,r=4*t-3))));r}
%Y Cf. A132838 (fourth-root); variants: A132831, A132835, A132839.
%K nonn
%O 0,2
%A _Paul D. Hanna_, Sep 10 2007