Function: prodeulerrat
Section: sums
C-Name: prodeulerrat
Prototype: GDGD2,L,p
Help: prodeulerrat(F,{s=1},{a=2}): product from primes p = a to infinity of
 F(p^s), where F is a rational function.
Doc: $\prod_{p\ge a}F(p^{s})$, where the product is taken over prime numbers
 and $F$ is a rational function.
 \bprog
 ? prodeulerrat(1+1/q^3,1)
 %1 = 1.1815649490102569125693997341604542605
 ? zeta(3)/zeta(6)
 %2 = 1.1815649490102569125693997341604542606
 @eprog
