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A sequence that remains integral

Source: Czech-Polish-Slovak 2006 Q5

April 27, 2013
calculusintegrationalgebra unsolvedalgebra

Problem Statement

Find the number of sequences (an)n=1(a_n)_{n=1}^\infty of integers satisfying an1a_n \ne -1 and an+2=an+2006an+1+1a_{n+2} =\frac{a_n + 2006}{a_{n+1} + 1} for each nNn \in \mathbb{N}.