27
There are two interwoven series.
A) 2,5,10,17 2 + 3 = 5 : 5 + 5 = 10 : 10 + 7 = 17
Each term takes the previous term and adds increasing odd numbers starting with 3.
B) 9,13,19....and then 27 9 + 4 = 13 : 13 + 6 = 19 : 19 + 8 = 27
Each term takes the previous term and adds increasing even numbers starting with 4.
27.
The next figure would be 21, followed by 11 & 10.
22
37.
It's, 7n+6
27.
The next figure would be 21, followed by 11 & 10.
18. The pattern is add 5, then subtract 1.
22
The next number in the sequence is 27.
18
37.
It's, 7n+6
This is a peculiar number sequence which follows the following rule: +7, -4, +8, -3, +9, -2... The next few functions would be +10, -1, +11, -0 And thus the next few numbers in the sequence would be 17+10=27, 27-1=26, and so on. The sequence in total goes 2, 9, 5, 13, 10, 19, 17, 27, 26, 37, 37.
20
119. un = (-n4 + 15n3 - 77n2 + 225n + 192)/6
The next number is 27. Nice puzzle! The reason is on discussion page, for those who are still working on it.