Question 920521
Do you mean *[tex \large a_n = 3(a_n - 1)] or *[tex \large a_n = 3(a_{n-1})]?


With the former interpretation we have a_2 = 3(4-1) = 9 and a_3 = 3(9-1) = 24. With the latter, we have a_2 = 12, a_3 = 36.