已知数列{an} an-anan+1-an+1=0 a1=1 求{2n/an}的前n项和 注：an+1的1加在n上

已知数列{an},若1/a1a2+1/a2a3+…+1/anan-1=n/anan+1,求证{an}为等差数列. 在数列{an}中,已知a1=1,a(n+1)=2an/(an+2),求数列{anan+1}的前n项和 已知数列{an}满足:a1=1,且an-an-1=2n,求(1)a2,a3,a4.(2)求数列{an}的通项anan都是a的下标n,an-1是a的下标n-1 已知数列an满足a1=1/2,anan+1=2an-an+1,求ann+1是下角标 已知数列满足a1=1,根号an-1-根号an=根号anan-1,求an 已知数列满足a1=1,√an-1 - √an = √anan-1 ,求an= 已知数列{an}中,a1=2,anan+1+an+1=2an已知数列{an}中,a1=2,an*(an+1)+(an+1)=2an 求{an}的通项公式 已知A1=1,A(n+1)=2An+3^n,求AnAn为数列，A(n+1)为An的后一项 已知数列{An}满足A平方n+1=AnAn+2（nEN*）,An〉0,且A2A4+2A3A5+A4A6=64,求a3+A5 已知数列an满足a1=1/2,anan-1=an-1-an,求数列an的通项公式 已知数列{an}满足a1=1,anan+1=2^n,则a9+a10 已知数列An中,A1=1,AnAn+1=(1/2)^n,1)求证{an}为等比数列 已知数列{an}满足a1=2且anan+1-2an=0球a2,a3,a4的值 高一数学题已知数列An满足:a1=1,a2=a(a＞0),数列Bn=AnAn+1 (1)若AN是...高一数学题已知数列An满足:a1=1,a2=a(a＞0),数列Bn=AnAn+1(1)若AN是等差数列,且B3=12,求a的值及AN通项共识（2）若An是等比数列,求Bn的前 已知数列An满足:a1=1,a2=a(a＞0),数列Bn=AnAn+1 (1)若AN是等差数列,且B3=12,求...已知数列An满足:a1=1,a2=a(a＞0),数列Bn=AnAn+1(1)若AN是等差数列,且B3=12,求a的值及AN通项共识（2）若An是等比数列,求Bn的前n项 数列An满足 根号下AnAn+1 +AnAn+2=4根号下AnAn+1 +An+1An+1 +数列An满足根号下AnAn+1 +AnAn+2=4根号下AnAn+1 +An+1An+1 +3根号下AnAn+1 且A1=1 A2=8 求An通项公式 数列题难难啊在数列{An}中,A1=1,AnAn+1=3n求An 数列an满足a1=2 ,a2=1,且( an-1 -an )/anan-1 =(an -an+1 )/anan+1 (n大于等于2),求a100 =