On the largest prime factor of quadratic polynomials

Abstract

Let $x$ denote a sufficiently large integer. We show that the recent result of Grimmelt and Merikoski actually yields the largest prime factor of $n^2+1$ is greater than $x^{1.317}$ infinitely often. As an application, we give a new upper bound for the number of integers $n⩽x$ which $n^2+1$ has a primitive divisor.

arXiv comment5 pages. Version 1 is another preprint which gives a weaker result