A115228 Non-squarefree numbers n such that 2n+1 is also non-squarefree (A013929).

4, 12, 24, 40, 60, 76, 84, 112, 144, 148, 162, 171, 180, 184, 212, 220, 256, 264, 292, 312, 328, 364, 387, 400, 412, 416, 420, 423, 436, 472, 480, 508, 512, 544, 580, 612, 616, 652, 684, 688, 712, 724, 760, 796, 808, 812, 832, 837, 840, 868, 904, 912, 924