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MathNet 2011 Question 21

Math Olympiad Vault · MathNet 2011

Question 21

Suppose $a_1 = 4$ and $a_{n+1} \ge a_n + n + 2$ for all natural numbers $n$. Show that
$$
\frac{1}{a_1} + \frac{1}{a_2} + \dots + \frac{1}{a_{2010}} \lt \frac{3}{2}.
$$