\(2^{n+7}\)

\begin{aligned}
\frac{4^n \times 8^{n+1}}{16^{n-1}}&=\frac{\left(2^2\right)^n \times\left(2^3\right)^{n+1}}{\left(2^4\right)^{n-1}} \\
& =\frac{2^{2 n} \times 2^{3 n+3}}{2^{4 n-4}} \\
& =2^{5 n+3-(4 n-4)} \\
& =2^{n+7}
\end{aligned}