Work

An improvement on the largest prime factor of $n^2+1$

Year: 2026
Type: preprint
Abstract: The study of the largest prime factor in polynomial sequences can be traced back at least to the late 19th century in the work of Störmer. Mahler (1933) and Chowla (1934) proved that the largest prime factor of $n^2+1$ grows at least as fast as $\log_2 n$. In 2023 we improved this to $(\log_2 n)^2/\log_3 n$. In this note we show the lower bound $(\log_2 n)^2/\log_4 n$, and that when this bound is nearly sharp it also holds for many prime factors of $n^2+1$.
Language: English
Open Access status: green
OpenAlex ID: W7206178452
Cites: 1
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Related to: 10