# Math Help - recursion formula's

1. ## recursion formula's

Can you write the recursion formula for this series? $a_n=\frac{1}{2^n}$

2. You give:

$a_n=\frac{1}{2^n}$.

This as it stands is a sequence not a series, and

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

RonL