已知数列{an},a1=1a2=2 ,a(n+1)=2an+3a(n-1) (1) 证明数列{an+a(n+1)}是等比数列

已知数列an中 a1=1a2=2 已知数列满足a1=1/2,an+1=2an/(an+1),求a1,a2已知数列满足a1=1/2,a(n+1)=2an/(an+1),求a1,a2;证明0 已知数列{an}中满足a1=1,a(n+1)=2an+1 (n∈N*),证明a1/a2+a2/a3+…+an/a(n+1) (1)数列{an}中,a1=1,a2=-3,a(n+1)=an+a(n+2),则a2005=____(2)已知数列｛an｝满足a1=1,a1×a2×a3…an=n^2,求an. 已知数列{a}中a1=1,an+1=an+2,求an?为什么a3-a2=2².已知数列{a}中a1=1,an+1=an+2,求an?为什么a3-a2=2². 已知数列{an}满足条件:a1=5,an=a1+a2+...a(n-1) n大于等于2,求数列{an}的通项公式 已知数列{an}满足a1=a,a2=b,a(n+1)=a(n+2)+an,求a2012 已知数列an满足an=1+2+...+n,且1/a1+1/a2+...+1/an 已知数列{an},an=2^n,则1/a1+1/a2+...+1/an等于多少? 已知数列{an}中、a1=1,an+1=2(a1+a2+...+an)求an的通项公式 已知数列{an}满足a(n+2)=a(n+1)-an,a1=1,a2=2,求a2005 已知数列{an}满足,a1=1,a2=2,a(n+1)=a(n+2)+an,求a2011? 已知数列{an}满足a1=1,a2=3,a(n+2)=a(n+1)-an,求S2012 已知正项数列｛a｝满足a1=1/2,且a(n+1)=an/(1+an) 1,求正项数列｛a｝的通项公式 2,求和:a1/1+a2/2+.2,求和:a1/1 + a2/2 +......+an/n 已知数列｛an｝满足：a1=1,且an-a（n-1）=2n.求a2,a3,a4.求数列｛an｝通项an 已知数列{an},a1=1a2=2 ,a(n+1)=2an+3a(n-1) (1) 证明数列{an+a(n+1)}是等比数列 已知数列An是等比数列,A2=2,A5=16,则A1*A2+A2*A3+.+An*A（n+1）=? 数列的,求通项的已知数列{an}中,a1=1,a2=2,a(n+2)=2/3a(n+1)+1/3an,求an