A039035 Numbers n such that representation in base 7 has same number of 1's and 2's.

0, 3, 4, 5, 6, 9, 15, 21, 24, 25, 26, 27, 28, 31, 32, 33, 34, 35, 38, 39, 40, 41, 42, 45, 46, 47, 48, 51, 63, 66, 67, 68, 69, 72, 79, 86, 93, 99, 105, 108, 109, 110, 111, 120, 127, 134, 141, 147, 150, 151, 152, 153, 156, 162, 168, 171, 172, 173, 174, 175, 178, 179