MathDB
2013-2014 Fall OMO #28

Source:

October 30, 2013
Online Math Openmodular arithmeticquadratics

Problem Statement

Let nn denote the product of the first 20132013 primes. Find the sum of all primes pp with 20p15020 \le p \le 150 such that (i) p+12\frac{p+1}{2} is even but is not a power of 22, and (ii) there exist pairwise distinct positive integers a,b,ca,b,c for which an(ab)(ac)+bn(bc)(ba)+cn(ca)(cb) a^n(a-b)(a-c) + b^n(b-c)(b-a) + c^n(c-a)(c-b) is divisible by pp but not p2p^2.
Proposed by Evan Chen