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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 2176 |
| 9 | 71424 |
| 10 | 1372160 |
| 11 | 20252672 |
| 12 | 255040512 |
| 13 | 2891180032 |
| 14 | 30447656960 |
| 15 | 303926476800 |
| 16 | 2914762424320 |
| 17 | 27113686958080 |
| 18 | 246327423270912 |
| 19 | 2196784154673152 |
| 20 | 19305427103907840 |
| 21 | 167673167523348480 |
| 22 | 1442534103145512960 |
| 23 | 12315082531044065280 |
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