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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 8 |
| 4 | 156 |
| 5 | 7480 |
| 6 | 898680 |
| 7 | 266674964 |
| 8 | 196750879896 |
| 9 | 360466213243792 |
| 10 | 1640421325318165822 |
| 11 | 18541481770815952051304 |
| 12 | 520535380394250894532873968 |
| 13 | 36296751650483051319011293939152 |
[0,1,8,156,7480,898680,266674964,196750879896, 360466213243792,1640421325318165822, 18541481770815952051304, 520535380394250894532873968, 36296751650483051319011293939152] |