a11Sn的知识精选

已知数列{an}的前n项和为Sn,且a1=1,Sn=,则a2017=(  )A.2016          B...
问题详情:已知数列{an}的前n项和为Sn,且a1=1,Sn=,则a2017=()A.2016          B.2017       C.4032          D.4034【回答】B∵a1=1,Sn=,∴当n≥2时,an=Sn-Sn-1=,可化为,∴=…==1,∴an=n....
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