Search a number
aban n.  and  triangular n.

First numbers that belong to both sets:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 120, 136, 153, 171, 190, 210, 231, 253, 276, 300, 325, 351, 378, 406, 435, 465, 496, 528, 561, 595, 630, 666, 703, 741, 780, 820, 861, 903, 946, 990, 1000405, 3000025, 4000206, 5000703, 11000395, 19000530, 27000226, 49000050, 60000535, 75000628, 84000241, 88000011, 122000010, 163000540, 205000876, 235000360, 241000035, 328000078, 330000895, 364000671, 366000040, 390000556, 396000153, 398000791, 405000030, 428000653, 437000266, 441000451, 458000245, 476000085, 505000090, 552000151, 565000920, 571000321, 586000495, 610000056, 630000756, 684000591, 688000965, 734000455, 792000100, 814000726, 818000128, 857000700, 915000031, 935000146, 973000441, 1021000266, 1098000091, 1131000580, 1167000516, 1210000221, 1346000670, 1411000003, 1448000205, 1474000660, 1479000078, 1553000046, 1577000880, 1590000636, 1597000870, 1614000520, 1663000956, 1753000866, 1781000403, 1841000860, 1852000230, 1912000041, 1969000881, 2075000410, 2159000616, 2169000316, 2200000278, 2317000701, 2515000503, 2527000686, 2749000026, 2952000703, 2965000521, 3050000253, 3055000861, 3197000703, 3199000078, 3201000078, 3203000703, 3294000361, 3458000703, 3550000191, 3576000165, 3606000426, 3645000271, 3702000081, 4023000150, 4141000515, 4172000185, 4188000960, 4284000766, 4289000653, 4312000545, 4545000811, 4566000141, 4837000546, 5055000426, 5071000278, 5146000525, 5313000903, 5377000551, 5490000505, 5526000756, 5554000315, 5577000078, 5889000601, 5978000496, 5985000528, 6025000878, 6119000625, 6160000510, 6186000835, 6549000681, 6910000461, 7002000291, 7128000901, 7621000611, 7696000080, 7736000691, 7857000690, 8105000221, 8235000280, 8590000128, 9030000078, 9602000331, 9882000820, 9891000276, 10002000330, 10125000753, 10183000695, 10225000506, 10566000396, 10620000930, 10687000701, 10729000855, 10858000566, 11284000651, 11455000480, 11593000315, 11685000628, 12145000878, 12179000485, 12299000703, 12307000716, 12334000330, 12699000028, 12736000200, 12794000703, 12798000078, 12802000078, 12806000703, 13102000626, 13311000703, 13701000880, 13801000591, 13977000415, 14078000503, 14262000495, 14548000600, 14773000105, 14862000621, 14867000830, 15239000910, 15386000490, 15533000640, 15736000906, 15817000870, 15958000575, 16174000440, 16495000896, 16706000655, 16992000378, 17208000370, 17226000078, 17265000753, 17318000778, 17397000246, 17531000376, 17734000285, 18249000490, 18630000906, 18658000551, 18710000403, 18752000970, 18916000260, 18952000705, 18997000660, 19612000275, 19655000778, 19764000336, 20348000778, 20412000225, 20631000015, 20681000376, 20843000706, 20909000265, 20996000740, 21333000403, 21448000941, 21803000610, 21859000416, 21900000970, 21949000921, 22073000995, 22106000511, 22272000985, 22362000940, 22384000320, 22875000778, 22936000753, 22981000078, 23217000355, 23253000378, 24168000585, 24741000235, 24880000915, 25059000385, 25476000675, 25511000140, 26310000745, 26837000326, 26933000095, 26959000503, 27247000080, 27311000041, 27424000306, 27465000006, 27642000375, 27722000845, 27953000790.

Some larger examples :