A031889 Lucky numbers with size of gaps equal to 6 (upper terms).

21, 31, 43, 49, 93, 99, 105, 111, 141, 169, 201, 211, 267, 273, 303, 327, 367, 391, 399, 415, 421, 427, 483, 495, 517, 535, 559, 651, 679, 685, 699, 723, 735, 787, 873, 903, 1029, 1093, 1101, 1123, 1189, 1209, 1281, 1291, 1309, 1329, 1395