Problem $1$

Consider the $4-$term recurrence relation

with

$,$

$,$

$,$ and

$.$

Problem $1($a$)$

Write a function four$\_$term$($y$0,$ y$1,$ y$2,$ n$)$ to return

in this recurrence, taking in the initial values,

$,$

$,$ and

$.$ You can assume that

$.$