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#85539e24-5fe2-4d1f-971b-a720f36fcccf基础解答题数列求和方法数列

2. 设数列{an}\{a_{n}\}是公差不为零的等差数列,其前nn项和为SnS_{n}a1=1a_{1}=1.若a1a_{1}a2a_{2}a5a_{5}成等比数列.
(1)求ana_{n}SnS_{n}
(2)设bn=1an+121(nN){b_n}=\frac{1}{a_{n+1}{}^{2}-1}({n\in {N^*}}),求数列{bn}\{b_{n}\}的前nn项和TnT_{n}