For a problem in quantum mechanics, I need to perform this integral: $$\int \frac{\psi(r)^2}{|r-R|} d^3r $$ where $\psi(r) = \frac{1}{\sqrt{\pi}a_0^{\frac{3}{2}}}e^{\frac{-r}{a_0}} $. So eventually it comes down to solve: $$ \frac{1}{\pi a_0^{3}} \int \frac{e^{\frac{-2r}{a_0}}}{|r-R|} d^3r $$
I tried the substitution with t = r-R, so I got: $$ \frac{1}{\pi a_0^{3}}e^{\frac{-2R}{a_0}} \int \frac{e^{\frac{-2t}{a_0}}}{|t|} d^3t $$
but I didn't know how to go further with it. The solution must be: $$\frac{1}{R}\left[1 - (1+\frac{R}{a_0})e^{\frac{-2R}{a_0}}\right]$$
Thanks in advance