设S1=1+1/12+1/22,S2=1+1/22+1/32 ...Sn=1+1/n2+1/(n+1)2,S=√S1+√

设数列{an}前n项和为Sn,已知(1/S1)+(1/S2)+.+(1/Sn)=n/(n+1),求S1,S2及Sn S1+S2+S3+……+S2008=?Sn=1/2×【(1-n/n)+(n/n+1)】 S1=4/1,S2=7/12,S 设sn为数列an的前n项和,Sn=(-1)^n-1/2^n,n属于N*,则(1)a3=? (2)S1+S2+...+S1 设Sn为数列an的前n项和,Sn=(-1)*nan-1/2*n,n属于N*,则(1)a3=?(2)S1+S2+...+S 已知Sn=1/2n(n+1),Tn=S1+S2+S3+.+Sn,求Tn. sn=n^2 求证1/s1+1/s2+1/s3……1/sn 已知s1=1,s2=1+2,s3=1+2+3,.sn=1+2+3+.+n,求Dn=s1+s2+s3,.sn An=2n-1,求证1/s1+1/s2+1/s3+…+1/sn fun(char *w,int n) { char t,*s1,*s2; s1=w; s2=w+n-1; while(s Sn=n^2+2n 求1/S1+1/S2+1/S3+……+1/Sn 高中数学数列证明已知Sn=2^n-1证明：n/2 - 1/3 < S1/S2 + S2/S3 +.+ Sn/Sn+1 < an=3n,Sn为前n项和,求1/S1+1/S2+1/S3+…+1/Sn.