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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | -2 |
| 4 | 0 |
| 5 | 40 |
| 6 | 0 |
| 7 | -3024 |
| 8 | 0 |
| 9 | 604800 |
| 10 | 0 |
| 11 | -262690560 |
| 12 | 0 |
| 13 | 217945728000 |
| 14 | 0 |
| 15 | -315323879270400 |
| 16 | 0 |
| 17 | 742997162299392000 |
| 18 | 0 |
| 19 | -2703345607134653644800 |
| 20 | 0 |
| 21 | 14552624755991316234240000 |
| 22 | 0 |
| 23 | -111913707637423660385894400000 |
| 24 | 0 |
[0,1,0,-2,0,40,0,-3024,0,604800,0,-262690560,0, 217945728000,0,-315323879270400,0, 742997162299392000,0,-2703345607134653644800,0, 14552624755991316234240000,0, -111913707637423660385894400000,0] |