#### Answer

$a_n=2^n$

#### Work Step by Step

RECALL:
The nth term of a geometric sequence is given by the formula:
$a_n=a_1(r^{n-1})$
where
$r$ = common ratio
$a_1$ = first term
$a_n$ = nth term
Notice that each term is twice the term before it.
This means that the sequence is geometric and that the common ratio is $2$.
The first term is $2$ so $a_1=2$.
Therefore the nth term of the sequence can be found using the formula:
$a_n=2(2^{n-1})
\\a_n=2^{n-1+1}
\\a_n=2^n$