等差数列An的首项为a1等于3公差等于2前n项和为Sn求数列.1/Sn的前n项和Tn
设首项为3,公差为2的等差数列,其前n项和为sn,求数列{1/sn}的前n项和Tn.
数列前n项和为sn,a1=1,an+sn是公差为2的等差数列,求an-2是等比数列,并求sn
已知公差不为0的等差数列{An}的首项A1=1,前n项和为Sn,若数列{Sn/An}是等差数列,求An?
等差数列{an},{bn}的前n项和分别为Sn,Tn,若Sn/Tn=2n/3n+1,则an/bn等于多少?
等差数列{an},{bn}的前n项和分别为Sn,Tn,若Sn/Tn=2n/3n+1,则a3/b3等于多少?
数列 an的前n项和为Sn,a1=1,an+1=2Sn 求数列{nan}的前n项和Tn
设数列an的首项a1等于1,前n项和为sn,sn+1=2n
已知数列{an}前n项和为Sn,a1=1,an+1=2Sn,求{nan}的前n项和Tn.
已知数列an的前n项和为Sn,a1=1,数列{an+Sn}是公差为2的等差数列
已知数列{an}的前n项和为sn,a1=1,数列{an+sn}是公差为2的等差数列
已知数列{an}的前N项和为Sn 且an+1=Sn-n+3,a1=2,设Bn=n/Sn-n+2前N项和为Tn 求证Tn
若等差数列{an}的首项为a1,公差为d,前n项的和为Sn,则数列(Sn/n)为等差数列,且通项