Hi there,

It has been long time since I had my math classes. However, I am trying to find a close form expression (if exists) of the following infinite product

$f(n) =\prod\limits_{i=n}^{\infty} (1-\frac{1}{q^i})$.

I am looking for an expression or approximation that represents the product. In particular, the case when q=2 and n=1 is of interest. But, the general equation is also important to me.

If you can refresh my memory on where I would find the needed material to do the above, or help with some clues, I would be really grateful.

Thanks,