$n^{3pq} - n \equiv 0$ (mod $3pq$), where p and q are prime and $n$ is any integer Find the minimum possible value of $p+q$
Let $p$, $q$ be prime numbers such that $n^{3pq} – n$ is a multiple of $3pq$ for all positive integers $n$. Find the least possible value of $p + q$.