(I)Sn+1=4an+2,当n=1时,a1+a2=4a1+2,a2=5;(1分)
当n=2时,a1+a2+a3=4a2+2,6+a3=22,a3=16;(2分)
(II)由an=
Sn+1?1 4
得,an+1=1 2
Sn+2?1 4
,an+1?an=1 2
an+21 4
an+1?an=1 2
an+2?1 4
an+1=1 2
(1 2
an+2?an+1),1 2
∴bn=
bn+1,1 2
=2∴数列{bn}是公比为2的等比数列.(4分)bn+1 bn
b1=
a2?a1=1 2
,3 2
∴bn=
?2n?1=3?2n?2(5分)3 2
(III)由(II)
3?2n?2=
an+1?an,1 2
=3 4
?an+1 2n+1
,令dn=an 2n
,d1=an 2n
=a1 2
1 2
∴数列{dn}是首项为
,公差为1 2
的等差数列.(7分)3 4
∴dn=
+(n?1)1 2
=3 4
3n?1 4
cn=
=22n+1
an?an+1
=1
dndn+1
(4 3
?1 dn
)1 dn+1
∴Tn=
(4 3
?1 d1
+1 d2
?1 d2
+…+1 d3
?1 dn
)=1 dn+1
(2?4 3
)=4 3n+2
(8分)8n 3n+2