$a_n = a_{n-1} + 4$, $a_1 = 3$

$a_n = 4a_{n-1}$, $a_0 = 3$

$a_n = 4a_{n-1}$, $a_1 = 3$

$a_n = 3a_{n-1}$, $a_1 = 4$