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APMO 2015 - Asian Pacific Mathematics Olympiad Question 3

APMO · APMO 2015 - Asian Pacific Mathematics Olympiad

Question 3

A sequence of real numbers $a_0,a_1,\ldots$ is good if:

(i) $a_0$ is a positive integer;

(ii) for every nonnegative integer $i$, either $a_{i+1}=2a_i+1$ or $a_{i+1}=a_i/(a_i+2)$;

(iii) $a_k=2014$ for some positive integer $k$.

Find the smallest positive integer $n$ for which a good sequence can have $a_n=2014$.

Proposed by Wang Wei Hua, Hong Kong.