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ON VALUES TAKEN BY THE LARGEST PRIME FACTOR OF SHIFTED PRIMES

Published online by Cambridge University Press:  15 August 2018

JIE WU*
Affiliation:
Department of Mathematics, Southwest University, 2 Tiansheng Road, Beibei, 400715 Chongqing, China CNRS UMR 8050, Laboratoire d’Analyse et de Mathématiques Appliquées, Université Paris-Est Créteil, 61 avenue du Général de Gaulle, 94010 Créteil Cedex, France email [email protected]
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Abstract

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Denote by $\mathbb{P}$ the set of all prime numbers and by $P(n)$ the largest prime factor of positive integer $n\geq 1$ with the convention $P(1)=1$. In this paper, we prove that, for each $\unicode[STIX]{x1D702}\in (\frac{32}{17},2.1426\cdots \,)$, there is a constant $c(\unicode[STIX]{x1D702})>1$ such that, for every fixed nonzero integer $a\in \mathbb{Z}^{\ast }$, the set

$$\begin{eqnarray}\{p\in \mathbb{P}:p=P(q-a)\text{ for some prime }q\text{ with }p^{\unicode[STIX]{x1D702}}<q\leq c(\unicode[STIX]{x1D702})p^{\unicode[STIX]{x1D702}}\}\end{eqnarray}$$
has relative asymptotic density one in $\mathbb{P}$. This improves a similar result due to Banks and Shparlinski [‘On values taken by the largest prime factor of shifted primes’, J. Aust. Math. Soc.82 (2015), 133–147], Theorem 1.1, which requires $\unicode[STIX]{x1D702}\in (\frac{32}{17},2.0606\cdots \,)$ in place of $\unicode[STIX]{x1D702}\in (\frac{32}{17},2.1426\cdots \,)$.

MSC classification

Type
Research Article
Copyright
© 2018 Australian Mathematical Publishing Association Inc. 

Footnotes

The author is supported in part by NSFC (grant no. 11771121).

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