Search a number
congruent n.  and  Duffinian n.

First numbers that belong to both sets:

21, 39, 55, 63, 65, 77, 85, 93, 111, 119, 125, 133, 143, 161, 175, 183, 189, 205, 215, 219, 221, 237, 245, 247, 253, 265, 279, 291, 299, 301, 309, 319, 323, 325, 327, 333, 335, 341, 343, 351, 365, 371, 381, 391, 399, 407, 413, 415, 437, 453, 469, 471, 485, 493, 505, 511, 517, 525, 527, 533, 535, 543, 549, 551, 559, 565, 567, 575, 583, 589, 597, 605, 623, 629, 651, 655, 669, 671, 685, 687, 689, 711, 721, 723, 731, 741, 749, 767, 777, 781, 791, 793, 799, 805, 813, 815, 831, 837, 845, 869, 871, 889, 893, 901, 903, 905, 917, 925, 927, 935, 943, 949, 959, 965, 975, 981, 985, 989, 999, 1003, 1007, 1025, 1029, 1037, 1047, 1053, 1055, 1057, 1073, 1079, 1081, 1085, 1101, 1105, 1111, 1119, 1127, 1133, 1135, 1141, 1143, 1157, 1159, 1165, 1175, 1183, 1189, 1191, 1197, 1205, 1207, 1241, 1247, 1253, 1255, 1261, 1263, 1271, 1285, 1295, 1309, 1317, 1325, 1333, 1343, 1349, 1351, 1357, 1359, 1375, 1379, 1387, 1389, 1391, 1393, 1397, 1405, 1407, 1411, 1413, 1415, 1421, 1443, 1445, 1461, 1463, 1469, 1477, 1495, 1501, 1513, 1517, 1519, 1525, 1533, 1535, 1541, 1565, 1573, 1575, 1589, 1591, 1623, 1629, 1631, 1633, 1639, 1645, 1647, 1649, 1651, 1655, 1659, 1661, 1677, 1679, 1685, 1687, 1703, 1705, 1711, 1727, 1731, 1735, 1751, 1765, 1767, 1775, 1781, 1791, 1799, 1805, 1807, 1813, 1821, 1829, 1837, 1839, 1853, 1855, 1893, 1903, 1909, 1919, 1925, 1927, 1939, 1943, 1957, 1967, 1971, 1981, 1983, 1991, 2005, 2007, 2015, 2021, 2023, 2035, 2047, 2059, 2061, 2071, 2077, 2101, 2117, 2119, 2125, 2127, 2133, 2135, 2159, 2165, 2173, 2181, 2183, 2189, 2191, 2197.

Some larger examples :