Question 89
Let the sequence $(u_n)$ be defined recursively by
$$
u_0 = 0,\ u_1 = 1,\ u_n = 2011u_{n-1} - u_{n-2} \quad \text{for } n \ge 2.$$
Find all the values of $n$ for which $u_n$ is prime.
$$
u_0 = 0,\ u_1 = 1,\ u_n = 2011u_{n-1} - u_{n-2} \quad \text{for } n \ge 2.$$
Find all the values of $n$ for which $u_n$ is prime.