# General formula for $\sum_{n=1}^{\infty} n^k r^n$ for arbitrary $k$

Is there a general formula for the above summation (in terms of $$r$$ and $$k$$)? I've read a very helpful answer on the general formula for $$\sum_{n=1}^{\infty} n r^n$$, and according to this answer, there was a general formula for arbitrary $$k$$; however, I couldn't find any references in there as to what it was.