a1=1,Sn=n^2an,求an
a1=1/2,an+1=an/an+2,求n/an的sn
已知a1=1,Sn=n^2an 求:an及Sn
已知数列an满足a1=1/2 sn=n平方×an 求an
已知数列{an},满足a1=1/2,Sn=n²×an,求an
已知数列an中 a1=-2且an+1=sn(n+1为下标),求an,sn
等差数列{an}中,a1+a2+a3=21,an-2+an-1+an=57,Sn=520,求n.
已知数列{an}a1=2前n项和为Sn 且满足Sn Sn-1=3an 求数列{an}的通项公式an
已知a1=3,an=Sn-1+2^n(n大于等于2),求an,Sn?
已知a1=1/2,Sn=n²an,求an
a1=1,Sn=n^2an,求an通项公式
已知数列An的前n项和Sn满足An+2Sn*Sn-1=0,n大于等于2,A1=1/2,求An.
数列{An},A1=1,A(n+1)=3An+4.求An和Sn.