设数列an的前n项和为Sn,Sn=a1(3^n-1)/2,且a4=54,则a1为?

数列｛an｝,中,a1=1/3,设Sn为数列｛an｝的前n项和,Sn=n（2n-1）an 求Sn 设数列an的首项a1等于1,前n项和为sn,sn+1=2n设数列an的首项a1等于1，前n项和为sn，sn+1=2n 设数列{an}的前n项和为Sn,a1=10,a(n+1)=9Sn+10 设数列{an}的前n项和为Sn,若a1=1,Sn=2an+Sn+(n∈N+),则a6= 设数列的前n项的和为sn,a1=2,根号sn-根号sn-1=根号2,求sn还要求an 设数列An的前n项和为Sn,已知a1=1,An+1=Sn+3n+1求证数列｛An+3}是等比数列 设数列【An】的前n项和为Sn,A1=10,An+1=9Sn+10.设Bn=lgAn,求证数列【Bn】为等差数列 设数列｛an}的前n项和为Sn,已知首项a1=3,且Sn+1+Sn=2an+1,试求此数列的通项公式an及前n项和Sn 设数列An的前n项和为Sn,且a1=1,An+1=1/3Sn,求数列an的通项公式. 设数列an的前n项和为Sn,已知a1=1,3an+1=Sn,求数列an的通项公式 设数列an的前n项和为Sn,已知a1=1,3an+1=Sn,求数列an的通项公式 设Sn为数列an的前n项和,Sn=kn*2+n,n∈N*,其中k为常数,求a1,an 设Sn是数列an的前n项和,已知a1=1,an=-Sn*Sn-1,（n大于等于2）,则Sn= 设数列{an}的前n项和为Sn,数列{Sn}的前n项和为Tn,满足Tn=2Sn-n^2,n∈N＊.求a1的值以及an的通项公式. 设数列{an}的前n项和为sn,sn=a1(3^n-2)/2(n≥1),a4=54,则a1= 已知Sn是数列an的前n项和,an的通向公式为2n 设Tn=（Sn/Sn+1） +（ Sn+1/Sn）-2设数列｛an｝的前项和为sn,a1=2,点（Sn+1,Sn）在直线(X/n+1)-(y/n)=1(n是正整数,1.求an的通项公式；2 .设Tn=（Sn/Sn+1） +（ Sn+1/Sn 数列an的前n项和为Sn,a1=1,an+1=2Sn 设bn=log3an,求数列bn的前n项和Tn数列an的前n项和为Sn,a1=1,an+1=2Sn 设bn=log3an,求数列bn的前n项和Tn 设等差数列{an}的前n项和为Sn 若a1=Sn>