This sequence follows the pattern: n! - 1, where n starts at 2. So: 2!-1 = 1, 3!-1 = 5 (but sequence shows 2), 4!-1 = 23 (but shows 6), 5!-1 = 119 (but shows 42). Actually, the pattern is each term is (previous term × next integer) - 1. More precisely: 1×2=2, 2×3=6, 6×7=42, 42×43=1806. The multiplier increases: ×2, ×3, ×7, ×43 where each multiplier is (previous term + 1).