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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 6 |
| 5 | 30 |
| 6 | 0 |
| 7 | 720 |
| 8 | 5760 |
| 9 | 0 |
| 10 | 362880 |
| 11 | 5417280 |
| 12 | 17107200 |
| 13 | 479001600 |
| 14 | 8885479680 |
| 15 | 32691859200 |
| 16 | 1307674368000 |
| 17 | 34151856076800 |
| 18 | 214585052774400 |
| 19 | 6402373705728000 |
| 20 | 192796754895360000 |
| 21 | 1542202547010048000 |
| 22 | 55105230485200896000 |
| 23 | 1944933030182596608000 |
[1,1,0,0,6,30,0,720,5760,0,362880,5417280, 17107200,479001600,8885479680,32691859200, 1307674368000,34151856076800,214585052774400, 6402373705728000,192796754895360000, 1542202547010048000,55105230485200896000, 1944933030182596608000] |