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Hungary-Israel Binational 1999\4

Source: Prove that a sequence containts only integers

October 30, 2008
inequalitiesalgebrapolynomialalgebra proposed

Problem Statement

c c is a positive integer. Consider the following recursive sequence: a_1\equal{}c, a_{n\plus{}1}\equal{}ca_{n}\plus{}\sqrt{(c^2\minus{}1)(a_n^2\minus{}1)}, for all n∈N n \in N. Prove that all the terms of the sequence are positive integers.