Discovering Coefficients of f(x)=5xarctan(3x) Power Series

[rocksteady]

Homework Statement

The function f(x)=5xarctan(3x) is represented as a power series. Find the first few coefficients in the power series.

Homework Equations

The power series is represented in the form sum(Cn*x^n)

The Attempt at a Solution

I've attempted to write the function as an integral, and split the 5x with the trignonometric component. After doing this (and writing a power series), I'm not getting the right answer. Is something wrong with my approach?

Thank you in advance.

 

[rock.freak667]

Take f(x)=tan^{-1}x and find the taylor series of it at \alpha=0 and the replace x by 3x and multiply by 5x after