p=2^n+1 is prime if 3^{(p-1)/2}+1\equiv 0 \pmod p
Source: Mathcenter Contest / Oly - Thai Forum 2012 sl-2 https://artofproblemsolving.com/community/c3196914_mathcenter_contest
November 13, 2022
number theoryprime
Problem Statement
Let and . Show that is a prime. (Zhuge Liang)