Prime divisors of sparse values of cyclotomic polynomials and Wieferich primes

JOURNAL OF NUMBER THEORY

卷:201

Article

Murty, M. Ram¹  Seguin, Francois¹ 

[1] Queens Univ, Dept Math, Kingston, ON K7L 3N6, Canada

关键词: Lucas sequences;    Wieferich primes;   

DOI  :  10.1016/j.jnt.2019.02.016

来源: Elsevier

【 摘 要 】

Bang (1886), Zsigmondy (1892) and Birkhoff and Vandiver (1904) initiated the study of the largest prime divisors of sequences of the form a(n) - b(n), denoted P(a(n) - b(n)), by essentially proving that for integers a > b > 0, P(a(n) - b(n)) >= n + 1 for every n > 2. Since then, the problem of finding bounds on the largest prime factor of Lehmer sequences, Lucas sequences or special cases thereof has been studied by many, most notably by Schinzel (1962), and Stewart (1975, 2013). In 2002, Murty and Wong proved, conditionally upon the abc conjecture, that P(a(n) - b(n)) >> n(2-epsilon) for any epsilon > 0. In this article, we improve this result for the specific case where b = 1. Specifically, we obtain a more precise result, and one that is dependent on a condition we believe to be weaker than the abc conjecture. Our result actually concerns the largest prime factor of the nth cyclotomic polynomial evaluated at a fixed integer a, P(Phi(n)(a)), as we let n grow. We additionally prove some results related to the prime factorization of Phi(n)(a). We also present a connection to Wieferich primes, as well as show that the finiteness of a particular subset of Wieferich primes is a sufficient condition for the infinitude of non-Wieferich primes. Finally, we use the technique used in the proof of the aforementioned results to show an improvement on average of estimates due to Erdos for certain sums. (C) 2019 Elsevier Inc. All rights reserved.

【 授权许可】

Free