I would imagine 66.667, as difference from 2 to 8 is 6, and the difference from 8 to 28 is 20. applying the fractional increase (20/6) to 20 gives you 66.667
The pattern is +4, 2x, +4, 2x, and so on. The next number is 32.
37
18
20
45
37
7
37
37
7.
27
28 (add on the prime number 11)