0,3,6,…,3*floor(n/3) 其中floor表示向下取整.在此n=500,floor(500/3)=166 于是500以内能被3整除的数有0,3,6,…,498.0,3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,69,72,75,78,81,84,87,90,9...