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MathNet 2026 — Part 04 Question 132

Math Olympiad Vault · MathNet 2026 — Part 04

Question 132

Determine all integers $n \geqslant 1$ as there is a $(a_{1}, a_{2}, \ldots, a_{n})$ permutation of $(1,2, \ldots, n)$ for the following condition: $$
k \mid a_{1}+a_{2}+\ldots+a_{k}
$$ for all $k \in\{1,2, \ldots, n\}$.