等差数列{an}的前n项和为Sn,且满足2S5-13a4+5a8=10,则下列数中恒为常数的是( )
设Sn是等差数列{an}的前n项和,S5=3(a2+a8),则a5a3的值为 ___ .
已知等差数列an满足a4=7,a3+a8=20,数列bn的前n项和为sn,且2sn=1-bn(n为正整数)
等差数列{an}的前n项和为Sn,且6S5-5S3=5,则a4=______.
设{an}是等差数列,{bn}是等比数列,记{an}{bn}的前n项和分别为Sn,Tn若a3=b3,a4=b4,且(S5
已知等差数列{an}满足a1=3.a4+a8=26,{an}的前n项和为Sn.求an及sn
设等差数列{an}的前n项和为Sn,若S3=9,S5=20,则a7+a8+a9=( )
设Sn是等差数列{an}(n∈N+)的前n项和,且a1=1,a4=7,则S5=______.
等差数列{An}的前n项和为Sn,且满足A3*A4=117,A2+A5=22 求通项An ;若数列{Bn}是等差数列,且
已知等差数列{an}的前n项和为Sn,若2a6=a8+6,则S7是( )
已知等差数列{an}的前n项和为Sn,且a2=p-2,a10=2-p,其中p为常数,则S5,S6的大小关系是
已知等差数列{an}的前n项的和为Sn,且S2=10,S5=55,则过点P(n,an)和Q(n+2,an+2)(n∈N*
已知等差数列{ an}的前n项和为Sn,且a2=-5,S5=-20.求通项公式