I have to integrate Lpr^-1.exp(-r/r0) with respect to r and show that it converges on Lpr0

What L p are is not important but r is a distance and r0 is a factor a constant that represents an attenuation length scale, deﬁned as the distance at which the reduction would be a factor of e. If that is important.

The hard part to me is integrating r^-1.exp(-r/r0) which turns out to be something called the exponential integral?

Can anyone offer help?