Question 3
The sequence $a_0,a_1,a_2,\ldots$ is defined by $a_0=20$, $a_1=100$, and
$$a_{n+2}=4a_{n+1}+5a_n+20.$$
Find the smallest positive integer $m$ such that $a_m-a_0,a_{m+1}-a_1,a_{m+2}-a_2,\ldots$ are all divisible by $1998$.
$$a_{n+2}=4a_{n+1}+5a_n+20.$$
Find the smallest positive integer $m$ such that $a_m-a_0,a_{m+1}-a_1,a_{m+2}-a_2,\ldots$ are all divisible by $1998$.