Solve by unfolding: a0=2, and, n>=1, a_n=7a_n-1.

We are told that the first term is 2. The next term is 7 (2) = 14; the third term is 7 (14) = 98. And so on. So, the first term and the common ratio (7) are known.

The nth term of this geometric series is a_n = 2 (7) ^ (n-1).

Check: What is the first term? We expect it is 2. 2 (7) ^ (1-1) = 2 (1) = 2. Correct.

What is the third term? We expect it is 98. 2 (7) ^ (3-1) = 2 (7) ^2 = 98. Right.