A031886 Lucky numbers with size of gaps equal to 4 (lower terms).

3, 9, 21, 33, 63, 69, 75, 111, 129, 159, 189, 201, 219, 231, 237, 285, 303, 327, 357, 429, 483, 537, 579, 615, 639, 651, 723, 735, 741, 777, 801, 819, 927, 933, 957, 975, 993, 1053, 1101, 1179, 1197, 1245, 1281, 1365, 1455, 1491, 1497, 1563