A168544 The nonprime halfs of even single (or even isolated) numbers.
1, 6, 9, 15, 21, 30, 36, 51, 54, 69, 75, 90, 96, 99, 114, 120, 135, 141, 156, 174, 210, 216, 231, 261, 285, 300, 309, 321, 330, 405, 411, 414, 429, 441, 510, 516, 525, 531, 546, 576, 615, 639, 645, 651, 639, 645, 651, 660, 714, 726, 741, 744, 804, 810, 834, 849
Offset: 1