What number comes next in the series: 9, 20, 42, 86, 174, ?

💡 Solution & Explanation

Each term is the previous term × 2 + 2: 9 × 2 + 2 = 20, 20 × 2 + 2 = 42, 42 × 2 + 2 = 86, 86 × 2 + 2 = 174. So the next term is 174 × 2 + 2 = 350.