数列{an}前n项和为sn,若sn/n=3s(n-1)/n-1(n≥2),a1=3,求an

已知数列{an}的前n项和为Sn,an+Sn=2,（n 已知数列an的前n项和为sn 若sn=2n-an,求an 已知数列{an}的前n项和为Sn,若a1=1/2,Sn=n^2an-n(n-1)求Sn,an 若数列｛an｝的前n项和为Sn,Sn=n(n+2),则a5= 已知数列｛an｝的前n项和为Sn,若Sn=n2+n,则通项公式an= 已知数列｛an｝中,a1=2,前n 项和为Sn,若Sn=n^2*an, 数列{an}前n项和为Sn,且2Sn+1=3an,求an及Sn 设数列an的前n项和为Sn,若Sn=1-2an/3,则an= 设数列{an}的前n项和为Sn,若a1=1,Sn=2an+Sn+(n∈N+),则a6= 已知数列 an前n项和为Sn,a1=1,Sn=2a(n+1),求Sn 已知数列前n项和为Sn,且Sn=-2n+3,求an及Sn 已知数列{an}的前n项和为Sn,若Sn=2^n-1,则a8= 已知数列an的前n项和为sn sn=3(的n次方)+1求数列an 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,且An=3^n+2n,则Sn等于 数列{an},an=1/[n*2^(n-1)].前N项和为Sn,求证Sn 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 已知数列{an}的前n项和为Sn,且Sn=lgn 求通项公式