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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 12 |
| 4 | 168 |
| 5 | 2880 |
| 6 | 64080 |
| 7 | 1723680 |
| 8 | 54633600 |
| 9 | 1992936960 |
| 10 | 82261267200 |
| 11 | 3790579161600 |
| 12 | 192895381324800 |
| 13 | 10744251136819200 |
| 14 | 650181362358528000 |
| 15 | 42476922345521664000 |
| 16 | 2979716339168464896000 |
| 17 | 223385082959833546752000 |
[0,0,2,12,168,2880,64080,1723680,54633600, 1992936960,82261267200,3790579161600, 192895381324800,10744251136819200, 650181362358528000,42476922345521664000, 2979716339168464896000,223385082959833546752000] |