Math
posted by Shadow .
Make a conjecture about the next item in each sequence.
1.4,6,9,13,18
I know that from 4 to 6 they added 2 and then from there each time the number you add is 1 more than the last one, but I don't know how to make a conjecture. Thanks

9 + 4 = 13
13 + 5 = 18
18 + 6 = ?