1/2+1/3≤(1/2)*2=11/4+...+1/7<=1/4*4=11/8+...+1/15<=1/8*8=1...............1+1/2+1/3+1/4+...+1/2 ^n≤1+1/2*2+1/4*4+^^^^^^+1/2^(n-1)*2^(n-1)=n(本题应该是1+1/2+1/3+1/4+...+1/(2 ^n-1)≤n ,否则n=1时1+1/2^1不小于等于1,本题出错!)
