Sn=2an+2n,a1=-1,求Sn
已知a1=1,Sn=n^2an 求:an及Sn
已知数列 an前n项和为Sn,a1=1,Sn=2a(n+1),求Sn
在数列{An}中,已知A1=1,An=2Sn^2/(2Sn-1),(n>=2),证明{1/Sn}是等差数列,并求Sn
数列{an}的前n项和为Sn,已知a1+2,Sn+1=Sn-2nSn+1Sn,求an
数列{an},前n项和sn,a1=2,a1、S(n+1)、4Sn成等差数列,求{an}通项公式、Sn
a1=1/2,an+1=an/an+2,求n/an的sn
已知数列an中 a1=-2且an+1=sn(n+1为下标),求an,sn
已知a1=3,an=Sn-1+2^n(n大于等于2),求an,Sn?
已知数列An的前n项和Sn满足An+2Sn*Sn-1=0,n大于等于2,A1=1/2,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满足a1=1/2 sn=n平方×an 求an
已知数列{an},满足a1=1/2,Sn=n²×an,求an