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MathNet 2024-part-06 — 165 problems (EN–VI) Question 164

Math Olympiad Vault · MathNet 2024-part-06 — 165 problems (EN–VI)

Question 164

For a positive integer $n$, let $\tau(n)$ be the number of positive divisors of $n$.

a) Find all positive integers $n$ such that $\tau(n) + 2023 = n$.

b) Prove that there exist infinitely many positive integers $k$ such that there are exactly two positive integers $n$ satisfying $\tau(kn) + 2023 = n$.