Need some help from Fibonacci experts...

[Thomas Baruchel]

> ggf(v)=local(l,m,p,q,B);l=length(v);B=floor(l/2);if(B<4,return(0));m=matrix(B,B,x,y,v[x-y+B+1]);q=qflll(m,4)[1];if(length(q)==0,return(0));p=sum(k=1,B,x^(k-1)*q[k,1]);q=Pol(Pol(vector(l,n,v[l-n+1]))*p+O(x^(B+1)));if(polcoeff(p,0)<0,q=-q;p=-p);q=q/p;p=Ser(q+O(x^(l+1)));for(m=1,l,if(polcoeff(p,m-1)!=v[m],return(0)));q

Thank you very much for that !!! Now, is there somewhere available a kind
of encyclopedy of basic algebraic "primitive" ogf (in order to recognize
factors of the denominator) ?

-- 
Thomas Baruchel