What comes next in this sequence?

[ParanoidUser]

1  4  8  13  21  30  36 ?

[peterbaccaro]

The next number in the sequence is 45.

This is because each number is calculated as the previous number plus the number of letters when the previous number is spelt.

The last number is 36 so "thirty six" has 9 letters.
Therefore, 36 + 9 = 45.

Each term increases by the number of letters in the previous term (ignoring any hyphens):

[CelioAmaral]

The Logic of the series is as follows :
1 + one (3 letters) = 4
4 + four (4 letters) = 8
8 + eight (5 letters) = 13
13 + thirteen (8 letters) = 21
21 + twenty one (9 letters) = 30
30 + thirty (6 letters) = 36
36 + thirty six (9 letters) = 45

So answer is 45