MathDB
2012-2013 Winter OMO #29

Source:

January 16, 2013
Online Math Opennumber theoryrelatively prime

Problem Statement

Let ϕ(n)\phi(n) denote the number of positive integers less than or equal to nn that are relatively prime to nn, and let d(n)d(n) denote the number of positive integer divisors of nn. For example, ϕ(6)=2\phi(6) = 2 and d(6)=4d(6) = 4. Find the sum of all odd integers n≤5000n \le 5000 such that n∣ϕ(n)d(n)n \mid \phi(n) d(n).
Alex Zhu
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