一位数:3,6
二位数:12,15,24,36
三位数:123,126,135,234,246,345,456
四位数:1236,1245,1356,2346,3456
以上的这些数都没有重复数字、位数不超过4并且能被3整除的数。而且这些数个数,十位,百位,千位上的数字对调后仍符合要求。所以共有
2+4*2!+7*3!+5*4!=172个
3,6,12,21,36,45,102,105,123,126,135,153,156,162,165,213,216,231,234,243,246,261,264,264,306,312,315,321,324,342,345,351,354,402,405,408,411,426,432,435,453,456,462,465,513,516,531,534,564,561,603,612,615,621,624,642,651
57