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

数列{An}满足a1=1/2,a1+a2+..+an=n方an,求an 设数列AN满足A1等于1,3(A1+a2+~+AN)=(n+2)an,求通向公式 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,a2=6,an+2=an+1-an,求a2013 数列{an}满足a1=3,a2=6,an+2=an+1-an,求a2008 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 数列an满足a1=1,a2=1/3,并且an(an-1+an+1)=2an+1an-1.则数列第2012项为? 数列an满足,a1=1/4,a2=3/4,an+1=2an-an-1(n≥2,n属于N*),数列bn满足b1 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. 数列an满足a1=1/2,a1+a2+a3……an=n^2an,则an 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=? 若数列｛an｝满足：a1=1,an+1=2an,n=1,2,3….则a1+a2+…+an=______. 若数列｛an｝满足a1=1,an+1=2an,n=1,2,3,……,则a1+a2+……+an=____________ 已知数列{an}满足a1+2a2+3a3+…+nan=n(n+1)(n+2),则a1+a2+a3+…+an=多少? 设数列【an】满足a1=1,3（a1+a2+a3+······+an）=（n+2）an,求通项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=?