Difference between revisions of "2011 IMO Shortlist Problems/A1"
(Created page with "==Problem== Given any set <math>A = \{a_1, a_2, a_3, a_4\}</math> of four distinct positive integers, we denote the sum <math>a_1 +a_2 +a_3 +a_4</math> by <math>s_A</math>. Let <...") |
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Latest revision as of 06:44, 28 October 2013
Problem
Given any set 
of four distinct positive integers, we denote the sum 
by 
. Let 
denote the number of pairs 
with 
for which 
divides . Find all sets 
of four distinct positive integers which achieve the largest possible value of .
Author: Fernando Campos, Mexico
