Which number among the given options does not belong to the following series?

4, 7, 13, 26, 49, 97

Given: 4, 7, 13, 26, 49, 97​

Logic: (1st number $$\times$$ 2) - 1 = 2nd number is follow.​

4 $$\times$$ 2 = 8, 8 - 1 = 7 (Follow)

7 $$\times$$ 2 = 14, 14 - 1 = 13 (Follow)​

13 $$\times$$​ 2 = 26, 26 - 1 = 25 $$\neq$$ 26 (Not Follow)

25 $$\times$$ 2 = 50 - 1 = 49 (Follow)​

49 $$\times$$​ 2 = 98, 98 - 1 = 97 (Follow)

So, 26 is not follow the series.

Thus, correct option is (d).