an的前n项和Sn,a1=7,an+1=(n+2)/nSn,证数列Sn/n是等比数列和S(n+1)=4an

an的前n项和Sn,a1=1,an+1=(n+2)/nSn,证数列Sn/n是等比数列和Sn+1=4an an的前n项和Sn,a1=7,an+1=(n+2)/nSn,证数列Sn/n是等比数列和S(n+1)=4an 数列an的前n项和为Sn,已知a1=1,an+1=(n+2)/nSn.求证：（1）数列{Sn/n}是等比数列（2）Sn+ 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}的前n项和为Sn，a1=1，an+1＝n+2nSn(n≥1，n∈N*)． 数列｛an}的前n项和为Sn,已知a1+2,Sn+1=Sn-2nSn+1Sn,求an 设数列{an}的前n项和为Sn,已知a1=5,且nSn+1=2n(n+1)+(n+1)Sn 已知数列an的前n项和为sn,若a1=1,nsn+1-（n+1）sn=n*n+cn（c是整数,n=1,2,3...）且s 等比数列的证明方式数列An的前n项和为Sn,A1=1,A(n+1)=2Sn+1,证明数列An是等比数列 数列{an}的前n项和记为sn,已知a1=1,An+1=(n+2)sn/n 1数列{sn/n}是等比数列 2sn+1=4 高中数列{An}前n项和Sn且A1=0 ,S(n+1)=4An+2.求证{A（n+1）-2An}为等比数列. 数列{an}前n项和为Sn,且an+Sn=-2n-1 证明{an+2}是等比数列