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B.Math 2008-Pigeonhole

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April 16, 2012
pigeonhole principle

Problem Statement

Let a1,a2,...,ana_1,a_2,...,a_n be integers . Show that there exists integers kk and rr such that the sum ak+ak+1+...+ak+ra_k+a_{k+1}+...+a_{k+r} is divisible by nn .