A043957 Numbers n such that 5 and 6 occur juxtaposed in the base 8 representation of n but not of n+1.

46, 53, 110, 117, 174, 181, 238, 245, 302, 309, 366, 375, 431, 437, 494, 501, 558, 565, 622, 629, 686, 693, 750, 757, 814, 821, 878, 887, 943, 949, 1006, 1013, 1070, 1077, 1134, 1141, 1198, 1205, 1262, 1269, 1326, 1333, 1390