Discrepancy of cartesian products of arithmetic progressions.
Some mean value theorems in the style of Bombieri-Vinogradov’s theorem are discussed. They concern binary and ternary additive problems with primes in arithmetic progressions and short intervals. Nontrivial estimates for some of these mean values are given. As application inter alia, we show that for large odd , Goldbach’s ternary problem is solvable with primes in short intervals with , , and such that has at most prime factors.
For any positive integer let ϕ(n) be the Euler function of n. A positive integer is called a noncototient if the equation x-ϕ(x)=n has no solution x. In this note, we give a sufficient condition on a positive integer k such that the geometrical progression consists entirely of noncototients. We then use computations to detect seven such positive integers k.
We prove that there is a small but fixed positive integer such that for every prime larger than a fixed integer, every subset of the integers modulo which satisfies and is contained in an arithmetic progression of length . This is the first result of this nature which places no unnecessary restrictions on the size of .