Difference between revisions of "2009 IMO Problems/Problem 3"
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Revision as of 06:22, 23 July 2009
Problem
Suppose that is a strictly increasing sequence of positive integers such that the subsequences
are both arithmetic progressions. Prove that the sequence is itself an arithmetic progression.
Author: Gabriel Carroll, USA
--Bugi 10:22, 23 July 2009 (UTC) Bugi