On gaps between quadratic non-residues in the Euclidean and Hamming metrics

The authors have recently introduced and studied a modification of the classical number theoretic question about the largest gap between consecutive quadratic non-residues and primitive roots modulo a prime p, where the distances are measured in the Hamming metric on binary representations of integers. Here we continue to study the distribution of such gaps. In particular we prove the upper bound l(p) <= (0.117198 ... + o(1)) log p/log 2 for the smallest Hamming weight l(p) among prime quadratic non-residues modulo a sufficiently large prime p. The Burgess bound on the least quadratic non-residue only gives l(p) <= (0.15163 ... + o(1)) log p/log 2. (C) 2013 Royal Dutch Mathematical Society (KWG). Published by Elsevier B.V. All rights reserved.