A023749 Plaindromes: numbers such that digits in base 7 are in ascending order.

0, 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 16, 17, 18, 19, 20, 24, 25, 26, 27, 32, 33, 34, 40, 41, 48, 57, 58, 59, 60, 61, 62, 65, 66, 67, 68, 69, 73, 74, 75, 76, 81, 82, 83, 89, 90, 97, 114, 115, 116, 117, 118, 122, 123, 124, 125, 130, 131, 132, 138, 139, 146, 171