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IMO 2003 — Complete Shortlist Question 20

IMO Shortlist · IMO 2003 — Complete Shortlist

Question 20

Let m be a fixed integer greater than 1. The sequence $ x_{0}, x_{1}, x_{2}, \ldots $ is defined as follows:

$$ x_{i}=\begin{cases}2^{i},&\text{if }0\leq i\leq m-1;\\\sum_{j=1}^{m}x_{i-j},&\text{if } i\geq m.\end{cases} $$

Find the greatest k for which the sequence contains k consecutive terms divisible by m.