Find the odd man out of the series 888, 440, 216, 104, 48, 22, 6 ?

In the given series,

 2nd term =  $\frac{1st term -8}{2} = \frac{888-8}{2}=440$  

 3rd term =  $\frac{2nd term -8}{2}=\frac{440-8}{2}=216$  

and so on...

Here 6th term =  $\frac{5th term -8}{2}=\frac{48-8}{2}=20$

 Therefore, 22 is wrong.