What number would replace the question mark in the series: 2, 5, 10, 19, 36, 69, 134, ?

The missing term is 263.

Each term follows next = 2 x term + a fixed drop.

Differences are 3, 5, 9, 17, 33, 65.

Each difference = 2 x previous - 1, so next = 2 x 65 - 1 = 129.

134 + 129 = 263.