数列{an}满足a1+3a2+3^2a3+……3^n-1an=n/3,【1】求{an}通项公式 【2】设bn=n/an,求{bn}前n项和sn数列{an}满足a1+3a2+3^2a3+……3^n-1an=n/3,【1】求{an}通项公式【2】设bn=n/an,求{bn}前n项和sn

已知数列{an}满足a1+2a2+3a3+…+nan=n(n+1)(n+2),则a1+a2+a3+…+an=多少? 若数列an满足,a1+a2+a3+.+an=3n-2求 an的通项公式 数列{an}满足:a1,a2-a1,a3-a2……,an-an-1构成以2为首项,3为公比的等比数列,求an 已知数列an满足a1+2a2+3a3+……+nan=2^n,求an 设数列｛an｝满足a1+2a2+3a3+.+nan=n(n+1)(n+2)求通项an 数列An 满足 a1+2a2+3a3+.+nan=n(n+1)(n+2) 求an 数列an满足a1+2a2+3a3+...+nan=n(n+1)(n+2) 求通项an急,谢谢解惑 若数列{an}满足a1+2a2+3a3+~~+nan=n(n+1)(2n+1),则an= 已知数列｛an｝的前n项和为Sn 1若数列｛an｝是等比数列,满足2a1+a3=3a2.a3+2是a已知数列｛an｝的前n项和为Sn1若数列｛an｝是等比数列,满足2a1+a3=3a2.a3+2是a2.a4的等差中项,求数列｛an｝的通向公式 已知数列{an}满足2a1+2^2a2+2^3a3+...+2^nan=4^n-1,则{an}的通项公式2a1+2^2a2+2^3a3就是2a1+4a2+8a3... 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? 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=? 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? 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） (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. 已知正数a1,a2,a3...an满足a1*a2*a3*...*an=1.求证：(2+a1)*(2+a2)*(2+a3)*...*(2+an)>=3^n