(1)设数列{an}的公比为q,
由题意可得a5=16,又a5-a4=8,
则a4=8,∴q=2.
∴an=2n-1,n∈N*.
(2)∵bn=log42n-1=
,n?1 2
由a1=1,得b1=0,数列{bn}为等差数列,
∴Sn=b1+b2+…+bn=
.n(n?1) 4
∵
=1 Sn
=4 n(n?1)
?4 n?1
,4 n
∴
+1 S2
+…+1 S3
1 Sn
=4(1?
+1 2
?1 2
+…+1 3
?1 n?1
)=4(1?1 n
).1 n