calculus - Finding the sum of a series with an n term in the numerator

Sum the series:

$$\sum_{n=1}^\infty\frac{2n}{7^{2n-1}}$$
I know it converges, but it's not a geometric series nor is it power/telescoping/alternating. I think having the n term in the numerator makes it difficult to solve.
I took calculus BC a number of years ago and I don't think I remember learning how to do this. Any help would be greatly appreciated!