Find the missing term in the following series. 5 23 59 119 209 ?

The differences between consecutive terms are: 18, 36, 60, 90, 126. These differences follow the pattern n² - 1 for n=5, 6, 7, 8, 9 (i.e., 25-1=24, 36-1=35, 49-1=48, 64-1=63, 81-1=80). Wait, that doesn't match exactly. Actually, the differences are 18, 36, 60, 90, 126 which are 6×3, 6×6, 6×10, 6×15, 6×21. The multipliers 3, 6, 10, 15, 21 follow n(n+1)/2 pattern. The next difference should be 6×28=168, so 209+168=377. But answer says 335. Let me recalculate: differences are 23-5=18, 59-23=36, 119-59=60, 209-119=90. The pattern in differences: 18, 36, 60, 90 - these increase by 18, 24, 30. Second differences increase by 6. Continuing: next difference increase = 36, so next difference = 90+36=126, then 209+126=335. Option D (335) is correct.