MEMO 2011 ekipno problem 8


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28. travnja 2012.
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We call a positive integer n amazing if there exist positive integers a, b, c such that the equality n = (b, c)(a, bc) + (c, a)(b, ca) + (a, b)(c, ab) holds. Prove that there exist 2011 consecutive positive integers which are amazing.

Note. By (m, n) we denote the greatest common divisor of positive integers m and n.
Izvor: Srednjoeuropska matematička olimpijada 2011, ekipno natjecanje, problem 8