已知数列 an前n项和为Sn,a1=1,Sn=2a(n+1),求Sn
已知数列 an前n项和为Sn,a1=1,Sn=2a(n+1),求Sn
数列{an}的前n项和为Sn,已知a1+2,Sn+1=Sn-2nSn+1Sn,求an
已知数列{an}a1=2前n项和为Sn 且满足Sn Sn-1=3an 求数列{an}的通项公式an
已知数列{an}的前n项和为Sn,且满足Sn=Sn-1/2Sn-1 +1,a1=2,求证{1/Sn}是等差数列
数列An的前n项和为Sn,已知A1=1,An+1=Sn*(n+2)/n,证明数列Sn/n是等比数列
已知数列An中,其前n项和为Sn,A1=1,且An+1=2Sn,求An的通项公式和Sn
已知数列{an}的各项都为正数,a1=1,前n项和Sn满足Sn-Sn-1=根号Sn+根号Sn-1(n≥2),求数列{an
已知数列{an}的前n项和为Sn,a1=1,Sn=2a(n+1)-1,求an=?
已知数列{an}的前n项和为Sn,a1=-23,Sn+1Sn=an-2(n≥2,n∈N)
题目;已知数列an的前n项和为Sn,a1=1,Sn=2a(n+1),则Sn=?
已知数列{an}的前n项和为Sn,又a1=2,nAn+1=sn+n(n+1),求数列{an}的通项公式
已知数列{an}的前n项和为Sn,且满足an+2Sn*Sn-1=0,a1=1/2.求证:{1/Sn}是等差数列