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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 0 |
| 4 | -56 |
| 5 | 0 |
| 6 | 15840 |
| 7 | 0 |
| 8 | -17297280 |
| 9 | 0 |
| 10 | 50791104000 |
| 11 | 0 |
| 12 | -327856732600320 |
| 13 | 0 |
| 14 | 4080179409546240000 |
| 15 | 0 |
| 16 | -89192941330901151744000 |
| 17 | 0 |
| 18 | 3193957788339335451033600000 |
| 19 | 0 |
| 20 | -177450861021098776794591068160000 |
| 21 | 0 |
| 22 | 14644425624059165645548485417369600000 |
| 23 | 0 |
[1,1,2,0,-56,0,15840,0,-17297280,0,50791104000,0, -327856732600320,0,4080179409546240000,0, -89192941330901151744000,0, 3193957788339335451033600000,0, -177450861021098776794591068160000,0, 14644425624059165645548485417369600000,0] |