记数列{an}的前n项和为Sn,且Sn=2(an-1),则a2=( ) A.4 发布时间:2017-05-03 09:27 │ 来源:www.tikuol.com 题型:选择题 问题: 记数列{an}的前n项和为Sn,且Sn=2(an-1),则a2=( )A.4B.2C.1D.-2