An=2n-1,求证1/s1+1/s2+1/s3+…+1/sn

问题描述:

An=2n-1,求证1/s1+1/s2+1/s3+…+1/sn

an=2n-1Sn = a1+a2+...+an = n^21/Sn = 1/n^2for n>=2,1/Sn