$\text{Prove That,}\;f(n) = \prod\limits_{i=1}^{n}(4i - 2) = \frac{(2n)!}{n!}$ 
$$\text{Prove That,}\;f(n) = \prod_{i=1}^{n}(4i - 2) = \frac{(2n)!}{n!}$$    

This is a problem from Elementary Number theory.    
My Work:
The statement is true for $i=1$. So, if it is true for $i=k$ it must be true for $ i = k+1$ . I am stuck here, any hint will be helpful.


Sorry I am not good in latex!!! This way of writing $\frac{2n!}{n!}$ helps in other problems also.
