A044160 Numbers n such that string 3,1 occurs in the base 7 representation of n but not of n-1.

22, 71, 120, 154, 169, 218, 267, 316, 365, 414, 463, 497, 512, 561, 610, 659, 708, 757, 806, 840, 855, 904, 953, 1002, 1051, 1078, 1149, 1183, 1198, 1247, 1296, 1345, 1394, 1443, 1492, 1526, 1541, 1590, 1639, 1688, 1737, 1786