已知数列{an}是等差数列,且a1=2,12an+1-12an=2(cos2π6 发布时间:2017-05-03 15:40 │ 来源:www.tikuol.com 题型:解答题 问题: 已知数列{an}是等差数列,且a1=2,12an+1-12an=2(cos2π6-sin2π6)(1)求数列{an}的通项公式;(2)令bn=an•3n+n,求数列{bn}的前n项和Tn.
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