设数列{An}满足 A1+3A2+3^2A3+……+3^n-1An=n/3 （n属于正整数） （1）求{An}的通项公式 （2）设Bn=n/An ,求{Bn}前n项和Sn.

设数列AN满足A1等于1,3(A1+a2+~+AN)=(n+2)an,求通向公式 设数列｛an｝满足a1+2a2+3a3+.+nan=n(n+1)(n+2)求通项an 设数列【an】满足a1=1,3（a1+a2+a3+······+an）=（n+2）an,求通项an 设数列{an}满足：a1+a2/2+a3/3+a4/4……+an/n=An+B,其中A、B为常数.数列{an}是否为等差数列? 问道数列题.设数列an满足a1+2a2+3a3+...+nan=2^n(n属于正自然数）,则数列an的通项是? 设数列{an}满足a1+a2/2+a3/3+.+an/n=n^2-2n-2,求数列{an}的通项公式 设数列{an}满足;a1+a2/2+a3/3+...+an/n=n^2-2n-2,求数列{an}的通项公式（a1,a2,a3...an中a后面都是下标） 设数列{an}满足a1+2a2+3a3+······nan=n^2求数列｛an}的通项公式 设数列｛an}满足a1+3a2+3^2a3+...+3^n-1an=n/3,求（1）数列{an}的通项公式（2）设bn=n/an求数列bn的前n项 设数列{an}满足a1=1a2=2an=1/3（an-1+2an-2）求an题目为设数列{an}满足a1=1，a2=2，an=1/3（an-1+2an-2）求an 设数列｛an｝满足a1+3a2+3^2a3+...+3^(n-1)an=n/3求an的通项 数列{an}满足a1=3/2,an+1=an2-an+1,求证：1/an=1/(an)-1 - 1/(an+1)-1数列{an}满足a1=3/2,an+1=an2-an+1,求证：1/an=1/(an)-1 - 1/(an+1)-1设Sn=1/a1+1/a2+...+1/an,n>2证明1 数列{an}满足：1/a1+2/a2+3/a3+…+n/an=2n(1)求通项公式an(2)设Sn=a1+a2+…+an,求1/S1+2/S2+…+n/Sn 高二数列题：设数列{an}满足an+1=an^2-nan+1,n为正整数,当a1>=3时,证明……设数列{an}满足an+1=an^2-nan+1,n为正整数,当a1>=3时,证明(2)1/(1+a1) + 1/(1+a2) + ……+1/(1+an) =< 1/2 已知数列{an}满足a1=1,a2=3,an+2=3an+1-2an求an 数列{an}满足a1=3/2,an+1=an2-an+1,求证：1/an=1/(an)-1 - 1/(an+1)-1 设Sn=1/a1+1/a2+...+1/an,n>2数列{an}满足a1=3/2,an+1=an2-an+1,求证：1/an=1/(an)-1 - 1/(an+1)-1设Sn=1/a1+1/a2+...+1/an,n>2证明1 已知等比数列{an}满足2a1＋a3＝3a2.且a3+2是a2.a4的等差中项.求数列已知等比数列{an}满足2a1＋a3＝3a2.且a3+2是a2.a4的等差中项. 求数列{an}的通项公式 设数列{an}的前n项和为sn,求S15 设数列｛an}满足a1+2a2+3a3+……+nan=2^n(n∈N*) 求数列｛an}的通项公式 设bn=n^2*an,求数列bn的前n项和