Which recurrence relation generates the sequence 1,3,9,27,…1, 3, 9, 27, \dots1,3,9,27,…?
an=an−1+2a_n = a_{n-1} + 2an=an−1+2
an=3an−1a_n = 3a_{n-1}an=3an−1
an=an−1+3a_n = a_{n-1} + 3an=an−1+3
an=2an−1+1a_n = 2a_{n-1} + 1an=2an−1+1