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MathNet 2023-part-05 — 191 problems (EN–VI) Question 1

Math Olympiad Vault · MathNet 2023-part-05 — 191 problems (EN–VI)

Question 1

Let $M \ge 1$ be a real number. Determine all natural numbers $n$ for which there exist pairwise distinct natural numbers $a, b, c \gt M$, such that
$$
n = (a, b) \cdot (b, c) + (b, c) \cdot (c, a) + (c, a) \cdot (a, b)
$$
(where $(x, y)$ denotes the greatest common divisor of natural numbers $x$ and $y$).