@flo in @Mariah‘s @answer, I noticed a pattern in the differences between the numbers. As she said, the difference between 4 and 5 is 1, the difference between 5 and 7 is 2, the difference between 7 and 11 is 4, and so on. I noticed a pattern of the differences (1, 2, 4, 8, 16…, etc.). If you look at that series it is the exact series of the powers of 2. [20=1 2 to the power of 0=1, 21=2, 22=4, 23=8…, etc., which givesyou the pattern 1, 2, 4, 8, 16, 32, 64, 128, 256 If you add three to each of those numbers, you end up with the original pattern.
So, 1+3=4, 2+3=5, 4+3=7 8+3=11, 16+3=19, and so on, 35, 67, 131,,,there are nine in the pattern, the ninth is the question mark. It is two to the ninth, add three, which would look like (2^9)+3=256+3=259,