因为你按照上一步1/nln>lnln(n+1)-lnln n1/2ln2+1/3ln3+...+1/nlnn>(lnln3-lnln2) + (lnln4-lnln3)+...+lnln(n+1)-lnlnn中间项lnln3,lnln4...lnlnn都一正一负都抵消了>lnln(n+1)-lnln2不明白可追问