an满足a1=1 a2=2/3 且2an-1an+1=an(an-1+an+1) 求an的通向公式已知f(x)=2x/(x^2+1) x1=1/2 xn+1=f(x) 求证(x1-x2)^2/x1x2 +(x2-x3)^2/x2x3 +……+（xn-xn+1)^2/xnxn+1

已知数列an满足an=1+2+...+n,且1/a1+1/a2+...+1/an 数列{An}满足a1=1/2,a1+a2+..+an=n方an,求an 若数列{an}满足a1=1,a2=5且an+2=an+1-an,求a2000 已知数列{an}满足a1=1,a2=3,an+2=3an+1-2an求an 已知递增数列{an}满足a1=1,(2an+1)=an+(an+2),且a1,a2,a4成等比数列.求an 数列｛an｝满足a1=1,且an=an-1+3n-2,求an 已知数列an满足an=1+2+...n,且（1/a1）+(1/a2）+...(1/an) 已知数列{an}满足:a1=1,a2=2,且 an+2=(2+cosnπ)(an-1)+3,n∈N+（1）求an 已知数列{an}满足:a1=1,a2=2,且 an+2=(2+cosnπ)(an-1)+3,n∈N+求通项公式an 【高中数学数列】已知数列an满足a1=1,a2=2,且an=an-1/an-2 (n大于等于3)则a2012=? 周期性函数递推设数列｛an｝满足a1=a2=1,a3=2,且对任意正整数n都有an*an+1*an+2≠1,又an*an+1*an+2*an+3=an+an+1+an+2+an+3,求a1+a2+…a100 设数列AN满足A1等于1,3(A1+a2+~+AN)=(n+2)an,求通向公式 数列{an}满足a1=3,a2=6,an+2=an+1-an,求a2013 数列{an}满足a1=3,a2=6,an+2=an+1-an,求a2008 已知正向数列｛an｝满足a1=1/2,且an+1=an/1+an.1/an=n+1,求和3/a1+3^2/a2+3^3/a3+……+3^n/an 设a1,a2,……,an(n>=2)是正实数,且满足a1+a2+……+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 = 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an