Which of the following is NOT a linear homogeneous recurrence relation?
an=3an−1a_n = 3a_{n-1}an=3an−1
an=an−1+an−2a_n = a_{n-1} + a_{n-2}an=an−1+an−2
an=an−12a_n = a_{n-1}^2an=an−12
an=5an−1−2an−2a_n = 5a_{n-1} - 2a_{n-2}an=5an−1−2an−2