Look at the first number in the sequence and determine how much each following term increases or decreases.

$\text{In this case, }\frac{1}{2} \text{ is the first term.}$

$\text{The terms decrease by a factor of }\frac{1}{2}.$

$\textit{t}(\textit{n})=\frac{1}{2}\left(\frac{1}{2}\right)^{\textit{n}-1}$

Note that each term decreases by $2$.