$\displaystyle a_{n+1}=a_n+\frac{1}{2^{n+1}}$

$\displaystyle n\geq 0$

$\displaystyle a_0=1$

I need to write $\displaystyle a_{n+1}$ in terms of $\displaystyle \frac{1}{2}a_n$

I've written out the first few terms... but I'm just not seeing it... apparently this is a geometric sequence if that helps...

Thanks.

Also, while I'm here, what's the TeX code to put a space? Cheers