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Phi(n)

Source: Indian IMOTC 2005 Day 5 Problem 2

September 23, 2005
number theory solvednumber theory

Problem Statement

Determine all positive integers n>2n > 2 , such that 12φ(n)1(mod6) \frac{1}{2} \varphi(n) \equiv 1 ( \bmod 6)