Sn=1/1.3+1/2.4+1/3.5+1/4.6+……+1/n(n+2)
Sn=1/1.3+1/2.4+1/3.5+1/4.6+……+1/n(n+2)
已知Sn=2+5n+8n^2+…+(3n-1)n^n-1(n∈N*)求Sn
求和:Sn=1*n+2*(n-1)+3*(n-2)+……+n*1
已知:Sn=1+1/2+1/3+……+1/n,用数学归纳法证明:Sn^2>1+n/2(n>=2,n∈N+)
Sn=1x2+3x2^2+5x2^3+…+(2n-1)x2^n sn=2sn-sn
已知数列{an}的前n项和为Sn=1+2+3+4+…+n,求f(n)= Sn /(n+32)Sn+1的最大值
an=(2^n-1)n,求Sn
求和:Sn=1*2*3+2*3*4+……+n(n+1)(n+2)
设数列{an}的前n项和为sn,已知a1+2a2+3a3+…+nan=(n-1)Sn+2n(n∈N*)
设Sn=-1+3-5+7-…+(-1)n(2n-1),则Sn=______.
数列{an}的前n项和记为Sn已知a1=1,an+1=n+2/n*Sn(n=1,2,3,…).求证:(1)数列{Sn/n
数列{an}的前n项和为Sn,已知a1=1,an+1=(n+2/n)Sn(n=1,2,3,…)求证{Sn/n}是等比数列