| List I: Frequency Range | List II: Types of Waves |
|---|---|
| (I) 1 × 1016 − 3 × 1021 Hz | (D) γ-rays |
| (II) 1 × 109 − 3 × 1011 Hz | (B) Microwaves |
| (III) 1 × 108 − 5 × 1022 Hz | (A) X-rays |
| (IV) 5 × 105 − 109 Hz | (C) Radio waves |

What comes next in the series?
\(2, 6, 12, 20, 30, \ ?\)
In a sequence of numbers, each term is generated by multiplying the previous term by 2 and then subtracting 1. If the first term is 3, what is the fourth term in the sequence?