11.4. Given 15 different pairwise coprime natural numbers from the interval . Prove that one of these numbers is prime.
Solution
Solution. Suppose this is not the case. Let these numbers be denoted by , and their smallest prime divisors by , respectively. Since all the numbers are pairwise coprime, these prime divisors are distinct. The first 15 prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, . This means that the largest of the prime divisors . Then the corresponding number , which contradicts the condition. Therefore, one of the numbers is prime.
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