Answer
The sequence is geometric with a common ratio of $3$.
The first four terms are:
$s_1=3$
$s_2=9$
$s_3=27$
$s_4=3^4=3(3)(3)(3)=27(3)=81$
Work Step by Step
Substitute $1, 2, 3,$ and $4$ to $n$ in the given formula to :
$s_1=3^1 = 3$
$s_2=3^2=3(3)=9$
$s_3=3^3=3(3)(3)=9(3)=27$
$s_4=3^4=3(3)(3)(3)=27(3)=81$
Notice the the next term is equal to $3$ times the current term.
This means that a common ratio of $3$ exists and the sequence is geometric.