先观察下面的解题过程，然后解答问题：
题目：化简：$(2+1)\left(2^2+1\right)\left(2^4+1\right)$
解：$(2+1)\left(2^2+1\right)\left(2^4+1\right)$

$$
\begin{aligned}
& =(2-1)(2+1)\left(2^2+1\right)\left(2^4+1\right) \\
& =\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right) \\
& =\left(2^4-1\right)\left(2^4+1\right) \\
& =2^8-1
\end{aligned}
$$


计算： $4 \times\left(3^2+1\right) \times\left(3^4+1\right) \times\left(3^8+1\right) \times \mathrm{...} \times\left(3^{64}+1\right)-\frac{3^{128}}{2}=$