Sum up the powered sines

Calculus Level 4

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

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