A031491 n-th number k which in base 8 has 2 fewer 0's than 7's.

63, 127, 191, 255, 319, 383, 447, 463, 471, 479, 487, 495, 503, 505, 506, 507, 508, 509, 510, 639, 703, 767, 831, 895, 959, 975, 983, 991, 999, 1007, 1015, 1017, 1018, 1019, 1020, 1021, 1022