\[R_{-a}\left(\mathbf{b};\mathbf{z}\right)=z_{n}^{-a}\sum_{N=0}^{\infty}\frac{{%
\left(a\right)_{N}}}{{\left(c\right)_{N}}}\*{T_{N}(b_{1},\dots,b_{n-1};1-(z_{1%
}/z_{n}),\dots,1-(z_{n-1}/z_{n}))},\]