Monthly Archives: November 2025

Let $n=pqrc$, where $p$, $q$, and $r$ are three distinct prime numbers, $p<q<r$, and $c$ is a positive integer. For any two distinct integers $1\le x<y\le n-1$, there exists $s$ which is a proper factor of $n$, $1<s<n$, such that … Continue reading →