What replaces the Question Mark

Genius Minds Wake Up !!!!
Answer this Question Correctly (#Brain Challenging#)
(-: The Post is your's :-)
1,1,2,3,8,?
What replaces the Question Mark "?"......

Answer : 28

1x1 =1 
1x2=2+1 =3
2x3=6+1+1=8
3x8 = 24 +2+1+1 =28