Bickley-Naylor
From specialfunctionswiki
The Bickely-Naylor functions $\mathrm{Ki}_n$ are defined by $$\mathrm{Ki}_n(x) = \displaystyle\int_0^{\frac{\pi}{2}} e^{-\frac{x}{\sin(\theta)}}\sin^{n-1}(\theta) \mathrm{d}\theta,$$ where $\pi$ denotes pi, $e^{\cdot}$ denotes the exponential, and $\sin$ denotes sine.
