TR-MO 2015 Problem 6

Find all positive integers $n$ such that for any positive integer $a$ relatively prime to $n$ , $2n^2 \mid a^n - 1$ .

Dataset text AI-MO AoPS. Quoted with source.

Solutions

No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.