已知数列{an}中,a1=1,前n项和为Sn,且点P(an,an+1)(n∈N* 发布时间:2017-04-28 17:12 │ 来源:www.tikuol.com 题型:解答题 问题: 已知数列{an}中,a1=1,前n项和为Sn,且点P(an,an+1)(n∈N*)在直线x-y+1=0上.(1)求证:{an}是等差数列;(2)设1S1+1S2+1S3+…+1Sn=Tn,求证Tn<2.