A043686 a(n) = (1/2)*(n-th number whose base-2 representation has exactly 12 runs).

1365, 2389, 2645, 2709, 2725, 2729, 2730, 2731, 2733, 2741, 2773, 2901, 3413, 4437, 4693, 4757, 4773, 4777, 4778, 4779, 4781, 4789, 4821, 4949, 5205, 5269, 5285, 5289, 5290, 5291, 5293, 5301, 5333, 5397, 5413, 5417