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IMOC 2021 N10

Source: IMOC 2021 N10

August 11, 2021
number theoryIMOC

Problem Statement

A prime is called perfect if there is a permutation a1,a2,,ap12,b1,b2,,bp12a_1, a_2, \cdots, a_{\frac{p-1}{2}}, b_1, b_2, \cdots, b_{\frac{p-1}{2}} of 1,2,,p11, 2, \cdots, p-1 satisfies biai+1ai(modp)b_i \equiv a_i + \frac{1}{a_i} \pmod p for all 1ip121 \le i \le \frac{p-1}{2}. Show that there are infinitely many primes that are not perfect.
Proposed By - CSJL