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Duffinian n.  and  iban n.

First numbers that belong to both sets:

4, 21, 27, 77, 100, 111, 121, 143, 144, 171, 201, 203, 217, 221, 242, 243, 247, 301, 323, 324, 327, 341, 343, 371, 377, 400, 403, 407, 417, 427, 471, 707, 711, 721, 722, 723, 741, 777, 1003, 1007, 1011, 1024, 1027, 1043, 1047, 1073, 1101, 1111, 1121, 1127, 1141, 1143, 1147, 1177, 1207, 1211, 1227, 1241, 1243, 1247, 1271, 1273, 1317, 1343, 1371, 1403, 1407, 1411, 1417, 1421, 1443, 1444, 1477, 1703, 1711, 1727, 1771, 2007, 2021, 2023, 2041, 2047, 2071, 2073, 2077, 2101, 2107, 2117, 2123, 2127, 2171, 2173, 2177, 2201, 2217, 2227, 2271, 2303, 2304, 2307, 2312, 2317, 2321, 2323, 2327, 2401, 2407, 2471, 2704, 2717, 2721, 2723, 2743, 2747, 2771, 2773, 3007, 3017, 3027, 3043, 3047, 3071, 3073, 3077, 3101, 3103, 3107, 3117, 3127, 3141, 3143, 3171, 3173, 3207, 3211, 3223, 3241, 3247, 3277, 3303, 3317, 3341, 3401, 3403, 3411, 3421, 3423, 3427, 3441, 3443, 3473, 3477, 3707, 3711, 3721, 3743, 3747, 3773, 4077, 4117, 4121, 4123, 4141, 4143, 4147, 4171, 4221, 4223, 4247, 4301, 4303, 4307, 4321, 4341, 4343, 4377, 4401, 4403, 4411, 4417, 4427, 4471, 4477, 4701, 4707, 4711, 4717, 4727, 4741, 4747, 4771, 4773, 4777, 7003, 7021, 7023, 7041, 7073, 7077, 7111, 7117, 7123, 7141, 7171, 7203, 7217, 7223, 7241, 7271, 7273, 7277, 7301, 7303, 7311, 7317, 7327, 7347, 7373, 7401, 7403, 7407, 7421, 7427, 7442, 7447, 7471, 7707, 7711, 7721, 7744, 7747, 7771, 7777, 10000, 10001, 10003, 10021, 10027, 10043, 10071, 10073, 10107, 10117, 10121, 10123, 10127, 10147, 10171, 10173, 10201, 10207, 10217, 10227, 10277, 10307, 10317, 10323, 10327, 10371, 10373, 10377, 10403, 10404, 10407, 10411, 10417, 10421, 10423, 10441, 10443, 10447, 10471, 10717, 10721, 10727, 10741, 10747, 10773, 10777, 11001.

Some larger examples :