已知数列an满足1/an+1-1/an=d,则称数列an为调和数列.已知数列1/xn为调和数列,且x1+x2+...+x20=200则x5+x16=?

已知数列{an}满足a1=1 an+1=an/(3an+1) 则球an 已知数列{an}中满足(An+1-An)(An+1+An)=16,且a1=1,an 已知数列{an}满足an+1=an+n,a1等于1,则an=? 已知数列{an}满足an+1=2an+3.5^n,a1=6.求an 已知数列an满足 a1=1/2,an+1=3an/an+3求证1/an为等差数列已知数列an满足 a1=1/2,an+1=3an/an+3求证1/an为等差数列 已知数列an满足a1=1,1/an+1=根号1/an^2+2,an>0,求an 已知数列｛an｝满足a1=1,an+1 -an+2an+1•an=0求通项 已知数列{an}满足a1=1,a2=3,an+2=3an+1-2an求an 已知数列{an}满足a1=2,an+1-an=an+1*an,那么a31等于 已知数列{an}满足a1=2,an+1=2an/an+2,则an等于多少 已知数列{an}满足a1=1/2,an+1=3an+1,求数列{an}通项公式 已知数列{An}满足A1=1,An+1=2An+2^n.求证数列An/2是等差数列 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a(n+1)=an+n,a1=1,则an= 已知数列an满足a1=1/2,(an+1-1)(an-1)-an+1+an=0求数列an的通项公式 已知数列[an]满足An+1=1+an /3-an ,且a1=1/3,求证数列[1/(an -1）]是等差数列,并求an 已知数列{an}满足a1=1,an+1=2an+1 1）求证：数列{an+1}为等比数列； 2) 求{an}的通项an 已知数列满足a1=1 ,an+1+2an=2 求an