a11an1的知识精选

已知数列{an}满足a1=1,an+1=则其前6项之和是(  )A.16   B.20   C.33   D....
问题详情:已知数列{an}满足a1=1,an+1=则其前6项之和是()A.16B.20C.33D.120【回答】C.a2=2a1=2,a3=a2+1=3,a4=2a3=6,a5=a4+1=7,a6=2a5=14,所以S6=1+2+3+6+7+14=33.知识点:数列题型:选择题...
热门标签