A037421 Numbers n such that the set of base 3 digits of n equals the set of base 9 digits of n.

1, 2, 9, 18, 81, 82, 83, 90, 99, 162, 163, 164, 171, 180, 729, 730, 731, 738, 739, 740, 747, 748, 749, 810, 811, 812, 819, 828, 891, 892, 893, 900, 909, 1458, 1459, 1460, 1467, 1468, 1469, 1476, 1477, 1478, 1539, 1540, 1541, 1548, 1557, 1620, 1621