The sequence is defined recursively. Find its general term. $t_1 = 3, t_n = 2(t_{n-1}) + 3n$
All I did was find the first couple of terms which are $3, 12, 33, 78, \dots$
The only thing common is that all are multiples of 3 but the sequence is neither arithmetic nor geometric. I've no idea how to solve a mixed sequence. Please help.