数列{an}前几项和为Sn,且Sn=n^2+2n+1,证明{an}不是等差数列

已知数列{an}中的前几项和为Sn且满足a1=0.5,an=-2Sn*S（n-1).证明数列｛1/Sn｝为等差数列,求S 已知数列{an}中,a2=2,前n项和为Sn,且Sn=n(an+1)/2证明数列{an+1-an}是等差数列 数列{an}中,a2=2,前n项和为sn,且sn=n(an+1)/2 证明{a-an}是等差数列 数列{an}前n项和为Sn,且an+Sn=-2n-1 证明{an+2}是等比数列 已知数列{an}的前n项和为Sn,且满足an+2Sn*Sn-1=0,a1=1/2.求证：{1/Sn}是等差数列 已知数列{an}的前n项和为Sn,且满足Sn=Sn-1/2Sn-1 +1,a1=2,求证{1/Sn}是等差数列 已知数列{An}的前n项和Sn=3n²-2n,证明数列{An}为等差数列 数列{an}前n项和Sn=npa[n](n是正整数),且a1不等于a2,(1)求p的值(2)证明{an}为等差数列 数列{an}满足a1=1,设该数列的前n项和为Sn,且Sn,Sn+1,2a1成等差数列.用数学归纳法证明:Sn=(2n- 设数列an的前n项和为Sn,a1=1,an=(Sn/n)+2(n-1)(n∈N*) 求证:数列an为等差数列, 数列{an}前n项和为Sn,且2Sn+1=3an,求an及Sn 设等差数列{an}的前 n项和为Sn,且 Sn=(an+1)^/2(n属于N*)若bn=(-1)nSn,求数列{bn}的