爱上海后花园

设数列{an}是首项为a1(a1>0),公差为2的等差数列,前n项和为Sn,且根号S1,根号S2,根号S3成等差数列,(1)求数列{an}的通项公式.(2)记bn=an/(2^n)的前n项和为Tn,求Tn.

aS1S2S3a=1an=2n1bn...

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