Solution
= Solution
The two conjugate roots satisfy $r^2=6r-4$, so $u_n=6u_{n-1}-4u_{n-2}$ with $u_0=2,u_1=6$. Induction gives $u_n\in\mathbb Z$.
= Solution
The two conjugate roots satisfy $r^2=6r-4$, so $u_n=6u_{n-1}-4u_{n-2}$ with $u_0=2,u_1=6$. Induction gives $u_n\in\mathbb Z$.