Finding the Maclaurin Series from a power series

Question

I have a Power Series of: $f(x) = \sum_{n=0}^\infty = \frac{nx^{3n}}{8n}$

I need to work backwards to find the original Maclaurin Series for $\int f(x)dx$.

I'm not sure how to go on about this, do I integrate each separately?

Any help would be much appreciated.