已知数列{an}的前n项和为Sn,a1=1,an+1=(λ+1)Sn+1(n∈N*,λ≠-2),且3a1,4a2,a3+13成等差数列.
(1)求数列{an}的通项公式;
(2)若数列{bn}满足anbn=log4an+1,数列{bn}的前n项和为Tn,证明:Tn<.