On the distribution of zeros of a sequence of entire functions approaching the Riemann zeta function

Abstract

In this paper we study the distribution of the zeros of each function G_{n}(z)≡1+2^{z}+...+n^{z}, n≥2, which approaches the Riemann zeta function for Rez<-1, and is closely related to the solutions of the functional equations f(z)+f(2z)+...+f(nz)=0. We determine the density of the zeros of G_{n}(z) on the critical strip where they are situated by using almost-periodic functions techniques. Furthermore, by using a theorem of Kronecker, we prove the existence in the critical strip of infinitely many rectangles for which we have found a formula to determine the number of zeros inside each rectangle with an error of ± 1 zero.