等比数列的前n项和为Sn,且4a1,2a2,a3成等差数列.若a1=1则S4等于

等比数列前n项和为Sn,且a1=1,a(n+1)=1/3.Sn求通项公式 已知数列an的前n项和为sn,且a1=1,a(n+1)=sn(n+2)/n,(n属于正整数)（1）求a2,a3,a4:(2)证明：数列sn/n是等比数列. 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. 设等比数列{an}的前n项和为Sn,Sn=[a1*（3^n-1）]/2,≥1,且a4=54,则a1=? 等比数列an的前n项和为Sn,且4a1,2a2,a3成等差数列.若a1等于1,则S4为多少? 等比数列的前n项和为Sn,a1为3/2,且S3,S5,S4成等差数列,求an 证明数列是等比数列数列前n项和为Sn,a1=1,a(n+1)=（n+2)Sn/n,求证Sn/n是等比数列, 已知数列{an}的前n项和记为Sn,已知a1=1,a(n+1)=[(n+2)/n]Sn,证明:(1)数列{Sn/n}是等比数列；(2)S(n+1)=4Sn 等比数列{an}的前n项和为sn,且4a1,2a2,a3成等差数列.若a1=1,则s4=? 等比数列｛An｝的前n项和为Sn且4a1 2a2 a3成等差数列若a1=1则S4=? 等比数列{an}的前n项和为Sn,且4a1,2a2,a3成等差数列.若a1=1,则S4等于多少? 等比数列（an)的前n项和为Sn ,且4a1,2a2,a3成为等差数列.若a1=1,则S4= 等比数列的前n项和为Sn,且4a1,2a2,a3成等差数列.若a1=1则S4等于 等比数列{an}的前n项和为Sn,且4a1,2a3,a3成等差数列,若a1=1,则S4=?思路,本人基础不好 等比数列｛an｝的前n项和为Sn,且4a1,2a2,a3成等差数列,若a1=1,则S4等于多少 等比数列{An}的前n项和为Sn,且4A1,2A2,A3成等差数列,若A1=1,求S4. 设正项等比数列{An}的首项a1=1/2,前n项和为Sn,且2*10S30 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