\[\mathop{\mathrm{i}^{n}\mathrm{erfc}}\left(z\right)=\int_{z}^{\infty}\mathop{%
\mathrm{i}^{n-1}\mathrm{erfc}}\left(t\right)\,\mathrm{d}t=\frac{2}{\sqrt{\pi}}%
\int_{z}^{\infty}\frac{(t-z)^{n}}{n!}e^{-t^{2}}\,\mathrm{d}t.\]