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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 337 |
| 6 | 8733 |
| 7 | 96478 |
| 8 | 668028 |
| 9 | 3413828 |
| 10 | 14054915 |
| 11 | 49171641 |
| 12 | 151422970 |
| 13 | 420674150 |
| 14 | 1073422309 |
| 15 | 2550004472 |
| 16 | 5699074284 |
| 17 | 12082541388 |
| 18 | 24462528078 |
| 19 | 47555986746 |
| 20 | 89173692795 |
| 21 | 161899772067 |
| 22 | 285517344145 |
| 23 | 490447009030 |
[0,0,0,1,337,8733,96478,668028,3413828,14054915, 49171641,151422970,420674150,1073422309, 2550004472,5699074284,12082541388,24462528078, 47555986746,89173692795,161899772067,285517344145, 490447009030] |