A044558 Numbers n such that string 5,4 occurs in the base 7 representation of n but not of n+1.

39, 88, 137, 186, 235, 279, 284, 333, 382, 431, 480, 529, 578, 622, 627, 676, 725, 774, 823, 872, 921, 965, 970, 1019, 1068, 1117, 1166, 1215, 1264, 1308, 1313, 1362, 1411, 1460, 1509, 1558, 1607, 1651, 1656, 1705, 1754, 1803