Classical IQ test

Question 10 / 10 3 Minute Reveal 0%

Complete the sequence: 3, 5, 11, 21, 43, ___ .

Each number alternates between ×2 −1 and ×2 +1: 3→5 (×2−1), 5→11 (×2+1), 11→21 (×2−1), 21→43 (×2+1), so 43→87 (×2+1).