A044035 Numbers n such that 6 and 7 occur juxtaposed in the base 10 representation of n but not of n+1.

67, 76, 167, 176, 267, 276, 367, 376, 467, 476, 567, 576, 667, 679, 769, 776, 867, 876, 967, 976, 1067, 1076, 1167, 1176, 1267, 1276, 1367, 1376, 1467, 1476, 1567, 1576, 1667, 1679, 1769, 1776, 1867, 1876, 1967, 1976, 2067