Integration of 

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> $$\frac{1}{2\pi i}\int\_{|z|=2} \frac{z^2}{(z-3)(z^n-1)}$$ where $n \in \mathbb{N}$ and $n \geq 5$
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**Solution i tried**- Here the singualrities of given function is in are all in $|z|\leq1$ and here $z=3$ is not a singularity so we have to integrate with $f(z)=\displaystyle\frac{z^2}{(z-3)}$. here i am not getting how to think about singularities in $(z^n-1)$ 

please help

Tahnk you