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| n | a(n) |
|---|---|
| 4 | 2 |
| 5 | 3 |
| 6 | 0 |
| 7 | 0 |
| 8 | 480 |
| 9 | 2400 |
| 10 | 0 |
| 11 | 0 |
| 12 | 7574400 |
| 13 | 66083040 |
| 14 | 0 |
| 15 | 0 |
| 16 | 896812758240 |
| 17 | 10058239033920 |
| 18 | 0 |
| 19 | 0 |
| 20 | 374736233227188672 |
| 21 | 5125335197750964000 |
| 22 | 0 |
| 23 | 0 |
[2,3,0,0,480,2400,0,0,7574400,66083040,0,0, 896812758240,10058239033920,0,0, 374736233227188672,5125335197750964000,0,0] |