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[EGMO3] GCD Bounds

Source: EGMO 2015, Problem 3

April 16, 2015
number theoryEGMOgreatest common divisorEGMO 2015

Problem Statement

Let n,mn, m be integers greater than 11, and let a1,a2,,ama_1, a_2, \dots, a_m be positive integers not greater than nmn^m. Prove that there exist positive integers b1,b2,,bmb_1, b_2, \dots, b_m not greater than nn, such that gcd(a1+b1,a2+b2,,am+bm)<n, \gcd(a_1 + b_1, a_2 + b_2, \dots, a_m + b_m) < n, where gcd(x1,x2,,xm)\gcd(x_1, x_2, \dots, x_m) denotes the greatest common divisor of x1,x2,,xmx_1, x_2, \dots, x_m.