Which of these is a linear recurrence relation?
an=an−1⋅an−2a_n = a_{n-1} \cdot a_{n-2}an=an−1⋅an−2
an=an−1a_n = \sqrt{a_{n-1}}an=an−1
an=3an−1+5a_n = 3a_{n-1} + 5an=3an−1+5
an=(an−1)2a_n = (a_{n-1})^2an=(an−1)2