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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 17 |
| 5 | 145 |
| 6 | 865 |
| 7 | 10325 |
| 8 | 88865 |
| 9 | 1357825 |
| 10 | 15335425 |
| 11 | 284963525 |
| 12 | 3993275825 |
| 13 | 87274812625 |
| 14 | 1462392957025 |
| 15 | 36716097543125 |
| 16 | 716611617346625 |
| 17 | 20309401097610625 |
| 18 | 452780458211706625 |
| 19 | 14290053364475013125 |
| 20 | 358439197464543820625 |
| 21 | 12462411363013047060625 |
[1,1,1,5,17,145,865,10325,88865,1357825,15335425, 284963525,3993275825,87274812625,1462392957025, 36716097543125,716611617346625,20309401097610625, 452780458211706625,14290053364475013125, 358439197464543820625,12462411363013047060625] |