26. Find the number of SDRs of the array
$$
\begin{array}{ccccccccccc}
1 & 2 & 3 & 4 & 5 & 6 & \cdots & n-2 & n-1 & n & \\
2 & 3 & 1 & 5 & 6 & 7 & \cdots & n-1 & n & 4 & (n \geqslant 6) \\
3 & 1 & 2 & 6 & 7 & 8 & \cdots & n & 4 & 5 &
\end{array}
$$
26. $6\left(\alpha_{1}^{n-3}+\alpha_{2}^{n-3}+2\right)$, where $\alpha_{1}=\frac{1+\sqrt{5}}{2}, \alpha_{2}=\frac{1-\sqrt{5}}{2}$.