an²=S2n-1
a1²=S1
a1=1、0
数列｛an｝是各项均不为0的=>
a1=1
an²=S2n-1
a2²=S3=a3+a2+a1
(a1+d)²=a1+2d+a1+d+a1
d²+2d+1=3d+3
d²-d-2=0
d=2、-1
数列｛an｝是各项均不为0的=>a2!=1-1=>
d=2
bn=1/(an·an+1)(n+1是角标吧?不是就别往下看了-.-b)
=1/[(2n-1)·(2n+1)]
=[1/(2n-1) - 1/(2n+1)]/2
Tn=1/2 · [1/1-1/3 + 1/3-1/5 +...+1/(2n-1) - 1/(2n+1)]
=1/2 · [1 - 1/(2n+1)]
=n/(2n+1)
(2):
λTn