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MathNet 2022-part-01 — 197 problems (EN–VI) Question 140

Math Olympiad Vault · MathNet 2022-part-01 — 197 problems (EN–VI)

Question 140

Find the number of all positive integers $4 \le n \le 2022$ that are not primes such that for any positive integer $k$ in the interval $[1, \sqrt{n}-1]$ the following holds: the number of ways to choose $k$ persons from a group of $n$ people is divisible by $n$.