117 1 - 16 - 81 - 117
Ans = 133 3 - 16 = 13(13 x 1) 16 - 42 = 26 (13 x 2) 42 - 81 = 39 (13 x 3) 81 - 133 = 52 (13 x 4) 133 - 198 = 65 (13 x 5)
1, 3, 8, 19,42, 89, (_)