Identify the number from among the given options that does NOT belong to the following series.
1, 3, 7, 15, 33

​​Given:
1, 3, 7, 15, 33
Logic: 1st number × 2 + 1 = next number.
Observe a pattern here:

1 × 2 + 1 = 3

3 × 2 + 1 = 7

7 × 2 + 1 = 15

15 × 2 + 1 = 31 $$\not = 33$$​​

So, the number that does not fit the pattern is 33.