Answer:The fifth term is just the next term. One possible answer can be obtained by looking at the differences in the first four terms: 2 (=3–1), 4 (=7–3) and 8 (=15–7). They are 2^1, 2^2 and 2^3. I would say the fifth term is 15+2^4 = 15 + 16 = 31.
Explanation: