6

Part of 1995 Turkey MO (2nd round)

Problems(1)

Turkish MO 1995 P6

Source: Turkish Mathematical Olympiad 2nd Round 1995

Find all surjective functions

f: \mathbb{N}\rightarrow \mathbb{N}

such that for all

m,n\in \mathbb{N}

f(m)\mid f(n) \mbox{ if and only if }m\mid n.

functionnumber theory unsolvednumber theory