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Infinitely prime numbers in a sequence

Source: 35th Austrian Mathematical Olympiad 2004, Round 1, problem 4

February 11, 2009
inductionnumber theoryprime numbersalgebra unsolvedalgebra

Problem Statement

The sequence <xn> < x_n > is defined through: x_{n \plus{} 1} \equal{} \left(\frac {n}{2004} \plus{} \frac {1}{n}\right)x_n^2 \minus{} \frac {n^3}{2004} \plus{} 1 for n>0 n > 0 Let x1 x_1 be a non-negative integer smaller than 204 204 so that all members of the sequence are non-negative integers. Show that there exist infinitely many prime numbers in this sequence.