[tex]\it u(2^{4n+2})=4 \Rightarrow u(2^{4n+2}+1)=5\ \ \ (1)\\ \\ u(6^n)=6\Rightarrow u(6^n-1)=5\ \ \ \ \ \ (2)\\ \\ (1),\ (2) \Rightarrow frac\c{\it t}ia\ se\ simplific\breve a\ prin\ 5,\ deci \ este\ reductibil\breve a,\ \forall n\in\mathbb{N}^*[/tex]
