A043146 Numbers n such that 3 and 4 occur juxtaposed in the base 7 representation of n but not of n-1.

25, 31, 74, 80, 123, 129, 172, 175, 217, 227, 270, 276, 319, 325, 368, 374, 417, 423, 466, 472, 515, 518, 560, 570, 613, 619, 662, 668, 711, 717, 760, 766, 809, 815, 858, 861, 903, 913, 956, 962, 1005, 1011, 1054, 1060, 1103