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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 14 |
| 3 | 84 |
| 4 | 896 |
| 5 | 10080 |
| 6 | 127904 |
| 7 | 1708224 |
| 8 | 23426816 |
| 9 | 325032960 |
| 10 | 4532831744 |
| 11 | 63353816064 |
| 12 | 886318555136 |
| 13 | 12404650352640 |
| 14 | 173642248822784 |
| 15 | 2430854346031104 |
| 16 | 34031138021113856 |
| 17 | 476430995352453120 |
| 18 | 6670004313281921024 |
| 19 | 93379882656019513344 |
| 20 | 1307317290804734590976 |
[1,0,14,84,896,10080,127904,1708224,23426816, 325032960,4532831744,63353816064,886318555136, 12404650352640,173642248822784,2430854346031104, 34031138021113856,476430995352453120, 6670004313281921024,93379882656019513344, 1307317290804734590976] |