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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 14 |
| 4 | 168 |
| 5 | 2776 |
| 6 | 56672 |
| 7 | 1342864 |
| 8 | 35866368 |
| 9 | 1089119616 |
| 10 | 39079100032 |
| 11 | 1656388518144 |
| 12 | 73919648645632 |
| 13 | 2888230034093056 |
| 14 | 104369370522809344 |
| 15 | 10598445084195061760 |
| 16 | 1502420051590162006016 |
| 17 | 39363517546114295169024 |
| 18 | -23019065875812133365235712 |
[0,1,2,14,168,2776,56672,1342864,35866368, 1089119616,39079100032,1656388518144, 73919648645632,2888230034093056, 104369370522809344,10598445084195061760, 1502420051590162006016,39363517546114295169024, -23019065875812133365235712] |