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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 6 |
| 3 | 15 |
| 4 | 30 |
| 5 | 51 |
| 6 | 93 |
| 7 | 156 |
| 8 | 240 |
| 9 | 387 |
| 10 | 597 |
| 11 | 870 |
| 12 | 1311 |
| 13 | 1920 |
| 14 | 2697 |
| 15 | 3873 |
| 16 | 5448 |
| 17 | 7422 |
| 18 | 10278 |
| 19 | 14016 |
| 20 | 18636 |
| 21 | 25098 |
| 22 | 33402 |
| 23 | 43548 |
| 24 | 57333 |
| 25 | 74757 |
| 26 | 95820 |
| 27 | 123780 |
| 28 | 158637 |
| 29 | 200391 |
| 30 | 254778 |
| 31 | 321798 |
| 32 | 401451 |
| 33 | 503490 |
| 34 | 627915 |
| 35 | 774726 |
| 36 | 960156 |
| 37 | 1184205 |
| 38 | 1446873 |
[1,3,6,15,30,51,93,156,240,387,597,870,1311,1920, 2697,3873,5448,7422,10278,14016,18636,25098,33402, 43548,57333,74757,95820,123780,158637,200391, 254778,321798,401451,503490,627915,774726,960156, 1184205,1446873] |