Sn=2an+2n,a1=-1,求Sn

a1=1/2,Sn=n^2an-n(n-1),求Sn和an a1=1,Sn=n^2an,求an a1=1,Sn=2an+1求Sn 已知数列 an前n项和为Sn,a1=1,Sn=2a(n+1),求Sn a1=1,n≥2时  ,sn2=an[sn-(1/2)]求sn Sn=2an+2n,a1=-1,求Sn 已知数列an的前n项和sn与通项an满足a1=2,sn+1sn=an+1,求sn 已知数列an中,a1=-2,an+1=Sn(n∈N+),求an和Sn的表达式 Sn=2an+n a1=1 求an其中{an}的前N项和为Sn 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 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紧急紧急!求救中!sos 已知数列an,若a1=1,nan+1=(n+2)Sn,求证Sn/n为等比数列已知数列an,若a1=1,nan+1=(n+2)Sn,求证数列Sn/n为等比数列,并且求Sn 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 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 数列an满足a1=1/3,Sn=n(2n-1)an,求an 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