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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 665 |
| 7 | 4655 |
| 8 | 37660 |
| 9 | 345660 |
| 10 | 3373629 |
| 11 | 37109919 |
| 12 | 443171498 |
| 13 | 5761229474 |
| 14 | 79709485141 |
| 15 | 1199252731963 |
| 16 | 19237203662248 |
| 17 | 327101074802216 |
| 18 | 5848216651372953 |
| 19 | 111064609625430747 |
| 20 | 2222478622302320382 |
| 21 | 46709011248199791062 |
| 22 | 1022898268873467547769 |
[1,1,2,6,24,120,665,4655,37660,345660,3373629, 37109919,443171498,5761229474,79709485141, 1199252731963,19237203662248,327101074802216, 5848216651372953,111064609625430747, 2222478622302320382,46709011248199791062, 1022898268873467547769] |