设Sn=1/2+1/6+1/12+…+1/n(n+1),且Sn*Sn+1=3/4,则n=多少?
设Sn为数列{an}的前n项和,且有S1=a,Sn+Sn-1=3n²,n=2,3,4,.
Sn=3+2^n Sn-1=3+2^(n-1).则Sn-Sn-1=?
设Sn=-1+3-5+7-…+(-1)n(2n-1),则Sn=______.
设Sn是数列an的前n项和,已知a1=1,an=-Sn*Sn-1,(n大于等于2),则Sn=
已知等差数列{an}的前n项和为Sn,且(2n-1)Sn+1 -(2n+1)Sn=4n²-1(n∈N*)
已知数列{an}的首项是a1=1,前n项和为Sn,且Sn+1=2Sn+3n+1(n∈N*).
设数列{an}前n项和为Sn,若s1=1,s2=2,且Sn+1-3Sn+2Sn-1=0(n>=2,且n∈N^*)判断数列
设S=1/2+1/6+1/12+...+1/n(n+1),且Sn*S(n+1)=3/4,则n的值为
设数列an的前n项和为sn,且a1为1 ,Sn+1=4an+2(n∈N正)
设数列{an}的前n项和为Sn,且2an=Sn+2n+1(n∈N*).
1 设Sn=1+2+3……+n,则f(n)=Sn/((n+7)*S(n+1))的最大值为
已知数列an的首项a1=5,前n项和为Sn,且S(n+1)=2Sn+n+5(n∈N*),求数列{an}的前n项和Sn,设