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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 30 |
| 4 | 552 |
| 5 | 14280 |
| 6 | 517680 |
| 7 | 25396560 |
| 8 | 1625662080 |
| 9 | 131681531520 |
| 10 | 13168185811200 |
| 11 | 1593350882323200 |
| 12 | 229442532323558400 |
| 13 | 38775788037405619200 |
| 14 | 7600054456464819148800 |
| 15 | 1710012252722891749632000 |
| 16 | 437763136697374129754112000 |
[0,0,2,30,552,14280,517680,25396560,1625662080, 131681531520,13168185811200,1593350882323200, 229442532323558400,38775788037405619200, 7600054456464819148800,1710012252722891749632000, 437763136697374129754112000] |