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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 24 |
| 5 | 0 |
| 6 | 0 |
| 7 | 2520 |
| 8 | 161280 |
| 9 | 0 |
| 10 | 1209600 |
| 11 | 219542400 |
| 12 | 10538035200 |
| 13 | 1556755200 |
| 14 | 559394035200 |
| 15 | 68652904320000 |
| 16 | 2933375142297600 |
| 17 | 2519452615680000 |
| 18 | 571411853236224000 |
| 19 | 58957325331480576000 |
| 20 | 2375999133429841920000 |
| 21 | 6705686160036864000000 |
| 22 | 1226258032083280035840000 |
[1,0,0,0,24,0,0,2520,161280,0,1209600,219542400, 10538035200,1556755200,559394035200, 68652904320000,2933375142297600,2519452615680000, 571411853236224000,58957325331480576000, 2375999133429841920000,6705686160036864000000, 1226258032083280035840000] |