\[I_{x}\left(a,b\right)=\frac{x^{a}(1-x)^{b}}{a\mathrm{B}\left(a,b\right)}\left(%
\cfrac{1}{1+\cfrac{d_{1}}{1+\cfrac{d_{2}}{1+\cfrac{d_{3}}{1+}}}}\cdots\right),\]