To describe the sequence 8, 16, 32, ..., we first observe that each term is double the previous term. This shows that the sequence is geometric.
The first term \( a_1 = 8 \) and the common ratio \( r = 2 \).
The general formula for the \( n \)-th term of a geometric sequence is given by:
\[ a_n = a_1 \cdot r^{(n-1)} \]
Substituting \( a_1 \) with 8 and \( r \) with 2, we have:
\[ a_n = 8 \cdot 2^{(n-1)} \]
Thus, the equation to describe the sequence is:
\[ a_n = 8 \cdot 2^{(n-1)} \]