A039032 Numbers n such that representation in base 7 has same number of 0's and 3's.

1, 2, 4, 5, 6, 8, 9, 11, 12, 13, 15, 16, 18, 19, 20, 21, 29, 30, 32, 33, 34, 36, 37, 39, 40, 41, 43, 44, 46, 47, 48, 52, 57, 58, 60, 61, 62, 64, 65, 67, 68, 69, 70, 78, 79, 81, 82, 83, 85, 86, 88, 89, 90, 92, 93, 95, 96, 97, 101, 106, 107, 109, 110, 111, 113, 114, 116