A043683 (1/2)(n-th number whose base 2 representation has exactly 6 runs).

21, 37, 41, 42, 43, 45, 53, 69, 73, 74, 75, 77, 81, 82, 83, 84, 86, 87, 89, 90, 91, 93, 101, 105, 106, 107, 109, 117, 133, 137, 138, 139, 141, 145, 146, 147, 148, 150, 151, 153, 154, 155, 157, 161, 162, 163, 164, 166, 167, 168, 172