1.已知数列an满足a1+3a2+...+3^(n-1)an=n/3(n属于N*),an通项公式为?2.已知数列an中,a1=1,a(n+1)=3an+3^n,an=______

已知数列an满足a1=1,a2=3,an+1.an-1=an,求a2013 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,a2-a1,a3-a2,...,an-an-1,...是首项为1,公比为1/3的等比数列.求an的表达式? 已知数列{an}满足a1+a2+...+an=n²an求其通项an 已知数列｛an｝满足a1,a2-a1,a3 -a2,…an-an-1,…是首相为1,公比 为三分之一的等比数列 1.求数列｛an｝的已知数列｛an｝满足a1,a2-a1,a3-a2,…an-an-1,…是首相为1,公比为三分之一的等比数列1.求数列｛a 已知等比数列{an}满足a1+a2=3,a2+a3=6,求这个数列的第7项a7 已知数列an满足an=1+2+...+n,且1/a1+1/a2+...+1/an (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an满足a1+2a2+3a3+……+nan=2^n,求an 已知数列{an}满足a1=1,a2=3,a(n+2)=a(n+1)-an,求S2012 已知数列{An}满足a1=1,An+1=2An+1.求A1+A2+A3+…+An的值 已知数列{an}满足a1+2a2+3a3+…+nan=n(n+1)(n+2),则a1+a2+a3+…+an=多少? 已知数列{an}满足a1=1,an=a1+2a2+3a3.+(n-1)an-1 (n>=2),则{an}的通项是什么 已知数列{an}满足a1=1,an=a1+2a2+3a3+……+(n-1)an-1 (n≥2)求an=? 已知,数列{an}满足a1=1,an+1=3an +1,证明:1/a1+1/a2+…+1/an 已知数列{an}满足a1=½,a1+a2+.+an=n²an,求其通项an 已知数列{an}满足a1=½,a1+a2+.+an=n²an,求其通项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=?