What will be come at the place of question mark? 1, 2, 5, 26, 677, ?

Each term is the square of the previous term plus 1: 1^2 + 1 = 2, 2^2 + 1 = 5, 5^2 + 1 = 26, and 26^2 + 1 = 677. Therefore the next term is 677^2 + 1 = 458330.