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#0bbcdb1b-8f6d-4a03-9efd-3e922a83a4ce基础填空题数列求和方法数列

6.已知数列{an}\{a_{n}\}满足a1=2a_{1}=2an+1=1+an1ana_{n+1}=\frac{1+{a_n}}{1-{a_n}},其前nn项和为TnT_{n},则T15=(T_{15}=(  ))