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Curzon n.  and  triangular n.

First numbers that belong to both sets:

1, 6, 21, 78, 105, 153, 210, 378, 561, 741, 861, 1485, 1653, 1770, 1953, 2850, 3081, 4005, 4950, 5565, 6105, 8646, 10878, 11325, 11781, 12090, 13041, 13530, 17766, 20706, 21321, 21945, 27966, 30381, 38781, 52326, 54285, 55278, 58653, 60726, 68265, 78210, 79401, 81810, 85905, 94830, 113526, 119805, 125250, 134421, 141246, 144453, 146070, 160461, 163878, 167910, 169653, 182106, 185745, 187578, 201930, 207690, 223446, 235641, 263901, 279378, 285390, 289941, 306153, 308505, 318801, 321201, 330078, 335790, 340725, 342378, 349866, 358281, 367653, 370230, 383250, 385881, 400065, 402753, 404550, 419070, 421821, 451725, 469965, 474825, 487578, 490545, 493521, 501501, 511566, 520710, 522753, 542361, 567645, 569778, 572985, 595686, 596778, 602253, 613278, 623286, 625521, 652653, 659526, 676866, 699153, 712221, 715806, 731445, 741153, 757065, 786885, 794430, 813450, 821121, 856086, 875826, 886446, 898470, 930930, 952890, 982101, 1011753, 1018878, 1041846, 1050525, 1057785, 1085601, 1088550, 1101870, 1116765, 1133265, 1148370, 1165101, 1169685, 1185030, 1197378, 1198926, 1226961, 1264845, 1274406, 1298466, 1313010, 1352190, 1355481, 1376970, 1386945, 1405326, 1432278, 1445850, 1457778, 1473186, 1476621, 1528626, 1599366, 1631721, 1637145, 1640766, 1646205, 1695561, 1779441, 1809753, 1849926, 1865346, 1867278, 1913946, 1949325, 1955253, 1965153, 2045253, 2067561, 2087946, 2100225, 2110485, 2149701, 2153850, 2187186, 2216565, 2267385, 2295153, 2301585, 2340366, 2357706, 2423301, 2429910, 2505441, 2512161, 2552670, 2559453, 2584401, 2591226, 2676141, 2687721, 2701650, 2736630, 2750685, 2795430, 2814378, 2845305, 2850078, 2857245, 2902845, 2907666, 2953665, 2965830, 3004926, 3039345, 3071481, 3083886, 3086370, 3158841, 3184026, 3227070, 3265290, 3267846, 3272961, 3280641, 3314025, 3391710, 3446625, 3454506, 3501981, 3509925, 3515226, 3573801, 3603270, 3667986, 3703281, 3708726, 3725085, 3760653, 3840606, 3885078, 3901821, 3960705, 4000206, 4037061, 4059825, 4096953, 4114146, 4119885, 4128501, 4157286, 4180386, 4189065, 4346826, 4367490, 4400061, 4408965, 4447653, 4489506, 4534566, 4561710, 4582878, 4591965, 4625361, 4803450, 4828278, 4921953, 4972281, 5038725, 5105610, 5134410, 5160078, 5286126, 5295885, 5348085, 5384121, 5436753, 5453253, 5576130, 5596185, 5713890, 5764710, 5774901.

Some larger examples :