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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 10 |
| 5 | 15 |
| 6 | 21 |
| 7 | 28 |
| 8 | 36 |
| 9 | 45 |
| 10 | 55 |
| 11 | 66 |
| 12 | 78 |
| 13 | 91 |
| 14 | 105 |
| 15 | 120 |
| 16 | 136 |
| 17 | 153 |
| 18 | 171 |
| 19 | 191 |
| 20 | 212 |
| 21 | 234 |
| 22 | 257 |
| 23 | 281 |
| 24 | 306 |
| 25 | 332 |
| 26 | 359 |
| 27 | 387 |
| 28 | 416 |
| 29 | 446 |
| 30 | 477 |
| 31 | 509 |
| 32 | 542 |
| 33 | 576 |
| 34 | 611 |
| 35 | 647 |
| 36 | 684 |
| 37 | 723 |
| 38 | 763 |
| 39 | 804 |
| 40 | 846 |
| 41 | 889 |
| 42 | 933 |
| 43 | 978 |
| 44 | 1024 |
| 45 | 1071 |
| 46 | 1119 |
| 47 | 1168 |
| 48 | 1218 |
| 49 | 1269 |
| 50 | 1321 |
| 51 | 1374 |
| 52 | 1428 |
| 53 | 1483 |
| 54 | 1540 |
| 55 | 1598 |
[1,3,6,10,15,21,28,36,45,55,66,78,91,105,120,136, 153,171,191,212,234,257,281,306,332,359,387,416, 446,477,509,542,576,611,647,684,723,763,804,846, 889,933,978,1024,1071,1119,1168,1218,1269,1321, 1374,1428,1483,1540,1598] |