Answer :

D3xt3R
Let's thing a little bit...

we have...

8

14

21

29

Can you see it now?!

[tex]8+6=14[/tex]

[tex]14+7=21[/tex]

[tex]21+8=29[/tex]

so

[tex]29+9=38[/tex]
8,14,21,29,38,
The missing sequence number is 38