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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 120 |
| 6 | 360 |
| 7 | 1680 |
| 8 | 10080 |
| 9 | 72576 |
| 10 | 604800 |
| 11 | 5702400 |
| 12 | 59875200 |
| 13 | 691891200 |
| 14 | 8717829120 |
| 15 | 118879488000 |
| 16 | 1743565824000 |
| 17 | 27360571392000 |
| 18 | 457312407552000 |
| 19 | 8109673360588800 |
| 20 | 152056375511040000 |
| 21 | 3005349539512320000 |
| 22 | 62444484876533760000 |
| 23 | 1360632459941314560000 |
[0,0,0,0,0,120,360,1680,10080,72576,604800, 5702400,59875200,691891200,8717829120, 118879488000,1743565824000,27360571392000, 457312407552000,8109673360588800, 152056375511040000,3005349539512320000, 62444484876533760000,1360632459941314560000] |