Can the present be absent?

Calculus Level 4

\[ \mathscr{E} = \displaystyle \int_{0}^{\infty} \dfrac{x^{2015}}{(1+x)^{2017}} \, dx \]

If \( \mathscr{E} \) can be represented in the form \( \dfrac{a}{b} \), with \( a, b\) being positive coprime integers, find \( a + b \).