1/(n+1)+1/(n+2)+1/(n+3)+...+1/2n的每一项都>=1/2n,共有n个,
所以1/(n+1)+1/(n+2)+1/(n+3)+...+1/2n>n*1/2n=1/2,
令m/24n=1/2的m=12n,m的最大值为12n.