Explanation

We'll look at the differences between terms:

5 − 2 = 3

10 − 5 = 5

17 − 10 = 7

26 − 17 = 9

So the differences are: 3, 5, 7, 9 → increasing by 2 each time (an arithmetic sequence).

The next difference should be: 11

Now add 11 to the last term:

26 + 11 = 37