A296244 Odd numbers k such that A007733(k) is even but 2^x == -1 (mod k) is insoluble.
15, 21, 35, 39, 45, 51, 55, 63, 69, 75, 77, 85, 87, 91, 93, 95, 105, 111, 115, 117, 119, 123, 133, 135, 141, 143, 147, 153, 155, 159, 165, 175, 183, 187, 189, 195, 203, 207, 213, 215, 219, 221, 225, 231, 235, 237, 245, 247, 253, 255, 259, 261, 267, 273, 275, 279, 285, 287
Offset: 1