Search a number
Ulam n.  and  unprimeable n.

First numbers that belong to both sets:

206, 324, 624, 1335, 1338, 1340, 1355, 1462, 1465, 1646, 1648, 1682, 1765, 1790, 1792, 1856, 1858, 1966, 1968, 2484, 2486, 2584, 2985, 3090, 3092, 3236, 3288, 3476, 3740, 3742, 3952, 3974, 3994, 4038, 4148, 4165, 4470, 4534, 4536, 4578, 4925, 5250, 5252, 5316, 5318, 5616, 5765, 5768, 5944, 5946, 6410, 6418, 6435, 6740, 6936, 6938, 7082, 7275, 7278, 7424, 7730, 7735, 7774, 7776, 8250, 8255, 8338, 8404, 8856, 8876, 9118, 9262, 9308, 9355, 9445, 9575, 9702, 9704, 9958, 9980, 9985, 10085, 10088, 10388, 10415, 10540, 10545, 10740, 10804, 10806, 10870, 10872, 11016, 11102, 11226, 11300, 11302, 11344, 11346, 11454, 11456, 11600, 11605, 11994, 11996, 12055, 12060, 12062, 12292, 12294, 12336, 12338, 12365, 12465, 12468, 12595, 12622, 12624, 12810, 12812, 12876, 12878, 13088, 13132, 13198, 13408, 13438, 13504, 13506, 13548, 13650, 13655, 13738, 13868, 13956, 13958, 13975, 14044, 14046, 14066, 14068, 14168, 14212, 14452, 14454, 14520, 14584, 14586, 14642, 14904, 14906, 14994, 15488, 15595, 15598, 15700, 15705, 15832, 15896, 15898, 15962, 15964, 15984, 15986, 16025, 16028, 16152, 16155, 16204, 16206, 16355, 16372, 16394, 16460, 16502, 16504, 16595, 16912, 16915, 17005, 17240, 17242, 17364, 17455, 17545, 17645, 17648, 17758, 17772, 17775, 17870, 17992, 17995, 18276, 18278, 18295, 18574, 18620, 18625, 18640, 18684, 18686, 18725, 18962, 19094, 19510, 19512, 19612, 19620, 19622, 19632, 19642, 19644, 19656, 19676, 19744, 19830, 19832, 20138, 20152, 20155, 20375, 20455, 20670, 20675, 20910, 20912, 20998, 21110, 21232, 21254, 21425, 21428, 21455, 21538, 21540, 21626, 21628, 21904, 22232, 22234, 22315, 22320, 22322, 22356, 22378, 22552, 22554, 22596, 22598, 22835, 22918, 23238, 23282, 23698, 23700, 23844, 23930, 23932, 23935, 24260, 24262, 24340, 24345, 24365, 24458, 24560, 24602, 24604, 24665, 24890, 24995, 24998, 25000, 25042, 25044, 25100, 25105, 25296, 25298.

Some larger examples :