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| n | a(n) |
|---|---|
| 5 | 1 |
| 6 | 0 |
| 7 | 420 |
| 8 | 37520 |
| 9 | 3656520 |
| 10 | 454406400 |
| 11 | 67651907400 |
| 12 | 11713973686800 |
| 13 | 2309360318565300 |
| 14 | 509886615053415600 |
| 15 | 124470953623133617500 |
| 16 | 33253861507512510664800 |
| 17 | 9642802738009988846098800 |
[1,0,420,37520,3656520,454406400,67651907400, 11713973686800,2309360318565300, 509886615053415600,124470953623133617500, 33253861507512510664800,9642802738009988846098800] |