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MathNet 2017-part-02 — 176 problems (EN–VI) Question 33

Math Olympiad Vault · MathNet 2017-part-02 — 176 problems (EN–VI)

Question 33

A sequence $a_0, a_1, a_2, \dots$ of positive real numbers is given such that
$$
a_1 = 1 - a_0, \quad a_{n+1} = 1 - a_n(1 - a_n) \quad \text{for all } n \ge 1.
$$
Prove that
$$
a_0 a_1 \cdots a_n \left( \frac{1}{a_0} + \frac{1}{a_1} + \cdots + \frac{1}{a_n} \right) = 1
$$
holds for every positive integer $n$.