If you would like to find f(4), you can calculate this using the following steps:
f(1) = 16
f(n) = 3 f(n-1) + 2
f(2) = 3 f(2-1) + 2 = 3 f(1) + 2 = 3 16 + 2 = 48 + 2 = 50
f(3) = 3 f(3-1) + 2 = 3 f(2) + 2 = 3 50 + 2 = 152
f(4) = 3 f(4-1) + 2 = 3 f(3) + 2 = 3 152 + 2 = 458
The correct result would be f(4) = 458.