(1)证明:因为an=2an-1+1(n≥2),所以an+1=2(an-1+1)(n≥2),
所以数列{an+1}是公比为2的等比数列.
(2)因为数列{an+1}是首项为a1+1=2,公比为2的等比数列,
所以an+1=2?2n-1=2n,所以bn=log2(an+1)=n.
所以
=1
bnbn+2
=1 n(n+2)
(1 2
?1 n
).1 n+2
所以Sn=
(1-1 2
)+1 3
(1 2
-1 2
)+1 4
(1 2
-1 3
)+…+1 5
(1 2
-1 n?1
)+1 n+1
(1 2
-1 n
)1 n+2
=
(1+1 2
-1 2
-1 n+1
)=1 n+2
.3n2+5n 4n2+12n+8