MathDB
2012-2013 Winter OMO #20

Source:

January 16, 2013
Online Math Opennumber theoryrelatively prime

Problem Statement

Let a1,a2,,a2013a_1,a_2,\ldots, a_{2013} be a permutation of the numbers from 11 to 20132013. Let An=a1+a2++annA_n = \frac{a_1 + a_2 + \cdots + a_n} {n} for n=1,2,,2013n = 1,2,\ldots, 2013. If the smallest possible difference between the largest and smallest values of A1,A2,,A2013A_1,A_2,\ldots, A_{2013} is mn\frac{m}{n}, where mm and nn are relatively prime positive integers, find m+nm+n.
Ray Li