a1=1,an=(1/2)a(n-1),n大于或等于2,求an 用构造等差或等比数列的方法算

数列{an},a1=3,an*a(n+1)=(1/2)^n,求an 数列{an}满足a1=2,a(n+1)=2an+n+2,求an 已知数列｛an｝中,a(n+1)=an+2^n,a1=3,求an a1=1,a(n+1)=2an+n^2+2n +2 求an A1=1,A(n+1)/An=(n+2)/n,求An? 已知a1=2 a(n+1)=2an+2^n+3^n 求an 1.a1=1 an=a1+2a2+.(n-1)an-1求an2.an+a（n+1）=1/2,a1=1,求an a1=2,a(n+1)=an^2求通项 2an+a(n-1)=3,a1=2 an=a1+(n-1)d 和Sn=n(a1+an)/2中an是什么意思? an=a1+(n-1)d 和Sn=n(a1+an)/2中an是什么 数列{An}满足a1=1/2,a1+a2+..+an=n方an,求an 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) 数列{an},a1=1,2a(n+1)=an +1,求通项an? 数列an满足a1=1,a(n+1)=an/[(2an)+1],求a2010 已知{an}满足a1=1,a(n+1)=2an+2,求an 已知数列{an},A1=1 A(n+1)=2an/an+2 求a5 a(n+1)=2an/3an+4,a1=1/4,求an