Problem

["James G. McLaughlin" <jgmclaug@math.uiuc.edu>]

This is probably not a bug question but I just do not know of the fastest
way to get pari to do it.

Let  F_{1}=F_{2}=1 and F_{n+1}= F_{n} + F_{n-1} for  n >= 2
      (The Fibonacci sequence)  

I wish to test the sequence { F_{2*i+1} : 1 <= i <= 69,700 }
for 13th powers. 

As you can imagine, as i gets up to 69,700,  F_{2*i+1} gets very big  
(around 10^(23,000)). I have not been able to
write a gp program that would do this in any reasonable time.

I wrote a very simple program in magma that would have done it in around 
3 - 4 hours (extrapolating) but it crashes around i = 52,000.

Am I missing something very simple and can gp do this easily or is it also
beyond gp to do this in a reasonable time?