English

Common values of a class of linear recurrence

Number Theory 2021-11-23 v1

Abstract

Let (an),(bn)(a_n), (b_n) be linear recursive sequences of integers with characteristic polynomials A(X),B(X)Z[X]A(X),B(X)\in \mathbb{Z}[X] respectively. Assume that A(X)A(X) has a dominating and simple real root α\alpha, while B(X)B(X) has a pair of conjugate complex dominating and simple roots β,βˉ\beta,\bar{\beta}. Assume further that α/β\alpha/ \beta and βˉ/β\bar{\beta}/\beta are not roots of unity and δ=logα/logβQ\delta = \log |\alpha|/ \log |\beta| \in \mathbb{Q}. Then there are effectively computable constants c0,c1>0c_0,c_1>0 such that the inequality anbm>an1(c0log2n)/n |a_n - b_m| > |a_n|^{1-(c_0 \log^2 n)/n} holds for all n,mZ02n,m \in \mathbb{Z}^2_{\ge 0} with max{n,m}>c1\max\{n,m\}>c_1.

Keywords

Cite

@article{arxiv.2111.11081,
  title  = {Common values of a class of linear recurrence},
  author = {Attila Pethő},
  journal= {arXiv preprint arXiv:2111.11081},
  year   = {2021}
}