A033004 Every run of digits of n in base 6 has length 2.

7, 14, 21, 28, 35, 252, 266, 273, 280, 287, 504, 511, 525, 532, 539, 756, 763, 770, 784, 791, 1008, 1015, 1022, 1029, 1043, 1260, 1267, 1274, 1281, 1288, 9079, 9086, 9093, 9100, 9107, 9576, 9583, 9597, 9604, 9611, 9828, 9835