JBMO-SL 2006 Problem 6

Prove that for every composite number $n>4$ , numbers $kn$ divides $(n-1)!$ for every integer $k$ such that $1\le k\le \lfloor \sqrt{n-1} \rfloor$ .

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.