{an}前n项和Sn=n^2-4n+4,求和Tn=1/a1·a2+1/a2·a3+……1/an·an-1
已知数列{an}前n项的和Sn=n的平方+12n,求和a1-a2+a3-a4+…+(-1)的(n+1)次方·an
已知数列{an}的前n项和sn=n^2+2n+3,求和1/a1+a2+1/a2+a3+1/a3+a4+.+1/an+an
已知数列an的前n项和为Sn=n^2+2n,求和:1/(a1*a2)+1/(a2*a3)+...+1/(an*a(n+1
设数列{an}的前n项和为sn,已知a1+2a2+3a3+…+nan=(n-1)Sn+2n(n∈N*)
设数列{an}的前n项和Sn=n^2-4n+1,则/a1/+/a2/+/a3/+……+/a10/=
数列an的前n项和为Sn,a1=t,2a(n+1)=-3Sn+4 求a2,a3 t为何值an等比
已知数列{an}前n项和Sn=n^2,记Pn=1/(a1*a2)+1/(a2*a3)+...+1/(an*an+1),求
高一数列求和数列{an}前n项和Sn=2^n-1,求a1^2+a2^2+…an^2
设数列an的前n项和为Sn 已知a1+2a2+3a3+……+nan=(n-1)Sn+2n
已知数列an满足a1+2a2+3a3+……+nan=n(n+1)(n+2),则它的前n项和Sn=?
已知数列{an}的前n项和Sn=n^2an(n≥2),而a1=1,通过计算a2,a3,猜想an等于?
设数列{an}的前n项和为Sn,并且满足2Sn=an²+n,an>0.(1)求a1,a2,a3.(2)猜想{a