The least square-free number in an arithmetic progression.
Let be a positive integer, denote any Dirichlet character . For any integer with , we define a sum analogous to high-dimensional Kloosterman sums as follows: where . The main purpose of this paper is to use elementary methods and properties of Gauss sums to study the computational problem of the absolute value , and give two interesting identities for it.
We establish upper bounds for certain trigonometric sums involving cosine powers. Part of these results extend previous ones valid for the sum . We apply our results to estimate character sums in an explicit and elementary way.
For a prime p and an absolutely irreducible modulo p polynomial f(U,V) ∈ ℤ[U,V] we obtain an asymptotic formula for the number of solutions to the congruence f(x,y) ≡ a (mod p) in positive integers x ≤ X, y ≤ Y, with the additional condition gcd(x,y) = 1. Such solutions have a natural interpretation as solutions which are visible from the origin. These formulas are derived on average over a for a fixed prime p, and also on average over p for a fixed integer a.