Question 176
Write down a set $S$ of positive integers, all greater than $1$, such that for each $x \in S$, $x$ is a proper divisor of $(P / x) + 1$, where $P$ is the product of all the elements of $S$. Your score is $2n$, where $n = |S|$.
Math Olympiad Vault · MathNet 2005 — Part 03