MathDB

6

Part of 2010 Indonesia MO

Problems(1)

Indonesia National Science Olympiad 2010 - Day 2 Problem 6

Source:

9/28/2010
Find all positive integers n>1n>1 such that τ(n)+ϕ(n)=n+1\tau(n)+\phi(n)=n+1 Which in this case, τ(n)\tau(n) represents the amount of positive divisors of nn, and ϕ(n)\phi(n) represents the amount of positive integers which are less than nn and relatively prime with nn.
Raja Oktovin, Pekanbaru
number theoryrelatively primenumber theory unsolved