(1)由题意知,
bn+1=an+1-
=1 an+1
=
an+12?1 an+1
=2(an?2(an2?1) an
)=2bn,1 an
b1=a1?
=1 a1
,8 3
∴数列{bn}是公比为2,首项为
的等比数列,其通项公式为bn=8 3
.2n+2 3
(2)由(1)有Sn+Tn=(a1?
)2+(a2?1 a1
)2+…+(an?1 a2
)2+2n1 an
=(
)2+(23 3
)2+…(24 3
)2+2n2n+2 3
=
(4n?1)+2n,n∈N*,64 27
为使Sn+Tn=
(4n?1)2+2n,n∈N*,当且仅当64 27
为整数.
4n?1 27
当n=1,2时,Sn+Tn不为整数,
当n≥3时,4n-1=(1+3)n-1=