1+2+3+4+.+n,求Sn
1+2+3+4+.+n,求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
数列求和:Sn=1/1*2*3+1/2*3*4+.+1/n*(n+1)*(n+2) 求Sn
求数列4,9,16,.,3n-1+2^n,.前n项的和Sn
已知an=(2n+1)*3^n,求Sn
(1).Sn=1+2×3+3×7...n(2^n-1),求Sn.
急求!高一数学题:已知数列{an},a1 = 1 , Sn是前n项和,Sn+1= Sn/( 3+4Sn) n >= 1
已知数列an的前n项和Sn,求数列的通项公式.(1)Sn=3n²-n (2)Sn=2n+1
已知Sn=2+5n+8n^2+…+(3n-1)n^n-1(n∈N*)求Sn
数列{an}前n项和为Sn,且2Sn+1=3an,求an及Sn
数列求和:sn=1+1/2+1/3+…+1/n,求sn
已知数列前n项和为Sn=1+2+2+3+3+3+4+4+4+4+5+5+5+5+.+n+n+n+n+n+.n,求Sn