Question 80
For a positive integer $n$, find the first decimal of the number:
$$
a_n = \frac{1}{n+1} + \frac{1}{n+2} + \dots + \frac{1}{2n}.
$$
$$
a_n = \frac{1}{n+1} + \frac{1}{n+2} + \dots + \frac{1}{2n}.
$$
MathNet 2012 Question 80
Math Olympiad Vault · MathNet 2012