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| n | a(n) |
|---|---|
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 8 |
| 7 | 56 |
| 8 | 512 |
| 9 | 4816 |
| 10 | 50336 |
| 11 | 572096 |
| 12 | 7048832 |
| 13 | 93609984 |
| 14 | 1333798272 |
| 15 | 20304005760 |
| 16 | 328957185024 |
| 17 | 5652803666688 |
| 18 | 102706725572096 |
| 19 | 1967499023510528 |
| 20 | 39636282097375232 |
| 21 | 837750752009506816 |
[0,0,0,8,56,512,4816,50336,572096,7048832, 93609984,1333798272,20304005760,328957185024, 5652803666688,102706725572096,1967499023510528, 39636282097375232,837750752009506816] |