[tex] (n+2) $ $|$ $ 91 \Rightarrow \left\| \begin{array}{c} (n+2) \in D_{91} \\ $dar$ \\ n\in \mathbb_{N}\Rightarrow$ $(n+2)\in \mathbb_{N} \end{array} \right |\Rightarrow (n+2)\in D_{91}^+ \Rightarrow \\ \\ \\\Rightarrow (n+2)\in \Big\{1;91\Big\} $ $\Big|-2 \Rightarrow n \in \Big\{-1;89\Big\},$ dar, $n\in \mathbb_{N} \Rightarrow $ \\ \\ $\Rightarrow \boxed{n \in \Big\{89\Big\}}[/tex]
