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MathNet 2020 — Math Olympiad Vault — Part 01 Question 67

Math Olympiad Vault · MathNet 2020 — Math Olympiad Vault — Part 01

Question 67

Let $N$ be a positive integer. Determine the number of pairs, $(a, b)$, of positive integers $a$ and $b$ such that the number
$$
\frac{ab}{a+b}
$$
is a divisor of $N$.