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NT with a set

Source: Swiss TST 2023 P2

September 8, 2023
number theory

Problem Statement

Let SS be a non-empty set of positive integers such that for any nSn \in S, all positive divisors of 2n+12^n+1 are also in SS. Prove that SS contains an integer of the form (p1p2p2023)2023(p_1p_2 \ldots p_{2023})^{2023}, where p1,p2,,p2023p_1, p_2, \ldots, p_{2023} are distinct prime numbers, all greater than 20232023.