Gene writes: << In Harvey Cohn, "Advanced Number Theory" a proof is given that the primes in arithmetic progression are equidistributed among residue classes in the sense that, for gcd(a,m) = 1, sum(1/p^s, p == a mod m) 1 ------------------------------- ==> ------ as s ==> 1. sum(1/p^s, all primes p) phi(m)

...

Thanks, Gene. If that's "Cohen" then I have the book & can look it up. --Dan