what is the 10th term of the sequence 64,16,4.....?
$$\small{\text{$
\begin{array}{rclcl}
a_1 &=& 64 &=& 4^3 \\
a_2 &=& 16 &=& 4^2 \\
a_3 &=& 4 &=& 4^1 \\
&& \cdots \\
a_n &&&=& 4^{4-n} \\
\\
\hline
\\
a_{10} &&&=& 4^{4-10} \\
a_{10} &&&=& 4^{-6}
\end{array}
$}}$$
