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Duffinian n.  and  semiprime

First numbers that belong to both sets:

4, 9, 21, 25, 35, 39, 49, 55, 57, 65, 77, 85, 93, 111, 115, 119, 121, 129, 133, 143, 155, 161, 169, 183, 185, 187, 201, 203, 205, 209, 215, 217, 219, 221, 235, 237, 247, 253, 259, 265, 289, 291, 299, 301, 305, 309, 319, 323, 327, 329, 335, 341, 355, 361, 365, 371, 377, 381, 391, 403, 407, 413, 415, 417, 427, 437, 451, 453, 469, 471, 481, 485, 489, 493, 497, 505, 511, 515, 517, 527, 529, 533, 535, 543, 551, 553, 559, 565, 579, 583, 589, 597, 611, 623, 629, 633, 635, 649, 655, 667, 669, 671, 685, 687, 689, 697, 707, 713, 721, 723, 731, 737, 749, 755, 763, 767, 779, 781, 785, 791, 793, 799, 803, 813, 815, 817, 831, 835, 841, 849, 851, 865, 869, 871, 889, 893, 899, 901, 905, 913, 917, 921, 923, 939, 943, 949, 955, 959, 961, 965, 979, 985, 989, 993, 1003, 1007, 1011, 1027, 1037, 1043, 1047, 1055, 1057, 1067, 1073, 1079, 1081, 1099, 1101, 1111, 1115, 1119, 1121, 1133, 1135, 1137, 1141, 1147, 1157, 1159, 1165, 1177, 1189, 1191, 1205, 1207, 1211, 1219, 1227, 1241, 1243, 1247, 1253, 1255, 1261, 1263, 1271, 1273, 1285, 1299, 1313, 1315, 1317, 1333, 1337, 1343, 1349, 1351, 1355, 1357, 1363, 1369, 1371, 1379, 1385, 1387, 1389, 1391, 1393, 1397, 1403, 1405, 1411, 1415, 1417, 1457, 1461, 1465, 1469, 1477, 1497, 1501, 1507, 1513, 1517, 1529, 1535, 1537, 1541, 1555, 1565, 1569, 1577, 1585, 1589, 1591, 1603, 1623, 1631, 1633, 1639, 1641, 1643, 1649, 1651, 1655, 1661, 1673, 1679, 1681, 1685, 1687, 1691, 1703, 1711, 1713, 1727, 1731, 1735, 1739, 1751, 1763, 1765, 1769, 1781, 1793, 1799, 1803, 1807, 1817.

Some larger examples :