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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 8 |
| 6 | 24 |
| 7 | 80 |
| 8 | 504 |
| 9 | 4600 |
| 10 | 36176 |
| 11 | 304888 |
| 12 | 2842472 |
| 13 | 29790752 |
| 14 | 331382672 |
| 15 | 3962130640 |
| 16 | 50186636768 |
| 17 | 680693513480 |
[1,0,0,0,8,24,80,504,4600,36176,304888,2842472, 29790752,331382672,3962130640,50186636768, 680693513480] |