Difference between revisions of "2010 IMO Problems/Problem 6"

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== See Also ==
 
== See Also ==
 
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{{IMO box|year=2010|num-b=5|After=Last Question}}
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[[Category:Olympiad Number Theory Problems]]
 
[[Category:Olympiad Number Theory Problems]]

Revision as of 16:51, 3 April 2012

Problem

Let $a_1, a_2, a_3, \ldots$ be a sequence of positive real numbers, and $s$ be a positive integer, such that \[a_n = \max \{ a_k + a_{n-k} \mid 1 \leq k \leq n-1 \} \ \textrm{ for all } \ n > s.\] Prove there exist positive integers $\ell \leq s$ and $N$, such that \[a_n = a_{\ell} + a_{n - \ell} \ \textrm{ for all } \ n \geq N.\]

Author: Morteza Saghafiyan, Iran

Solution

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See Also

2010 IMO (Problems) • Resources
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Problem 5
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[[2010 IMO Problems/Problem {{{num-a}}}|Problem {{{num-a}}}]]
All IMO Problems and Solutions