OFFSET
0,2
PROG
(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}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Sep 10 2007
STATUS
approved