#### Answer

$a_n=1+(n-1)2=2n-1$

#### Work Step by Step

RECALL:
The nth term of an arithmetic sequence is given by the formula:
$a_n=a_1+(n-1)d$
where
$d$ = common difference
$a_1$ = first term
$a_n$ = nth term
Notice that the terms increase by $2$.
This means that the sequence is arithmetic and that the common difference, $d$, is $2$.
The first term is $1$ so $a_1=1$.
Therefore the nth term of the sequence can be found using the formula:
$a_n=1+(n-1)2$