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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 4 |
| 7 | 120 |
| 8 | 160 |
| 9 | 12096 |
| 10 | 20160 |
| 11 | 604800 |
| 12 | 403200 |
| 13 | 456192 |
| 14 | 5322240 |
| 15 | 217945728000 |
| 16 | 581188608000 |
| 17 | 139485265920 |
| 18 | 232475443200 |
| 19 | 13857951744000 |
| 20 | 508124897280000 |
| 21 | 6192841475358720 |
| 22 | 113535427048243200 |
| 23 | 187333454629601280000 |
[1,1,1,1,2,4,4,120,160,12096,20160,604800,403200, 456192,5322240,217945728000,581188608000, 139485265920,232475443200,13857951744000, 508124897280000,6192841475358720, 113535427048243200,187333454629601280000] |