problem with polynomials

["Kostas Patsakis" <kpatsak@gmail.com>]

Hello,

I'm trying to use pari in order to set the coefficients of a
polynomials from a vector.
eg if the vector is [1 0 3] then f(x)=1+x^2
i tried something like this:
poly(t)=0*t;
for(cnt=1,len,{
        poly(t)=poly(t)+t^(cnt-1)*a[cnt];})

but pari does not like it...
i keep getting ***   deep recursion: poly(t)

any ideas on how I can do it?