Sum up the powered sines

Calculus Level 3

$\large \lim_{n\to \infty} \sum_{r=1}^{n^2} \frac 1r \sin \left(\frac{2017 r^2}{n^2}\right)$

If the value of the limit above is $\dfrac{a \pi}{b}$ , where $a$ and $b$ are coprime positive integers, then what is $a + b?$