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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 6 |
| 3 | -6 |
| 4 | 120 |
| 5 | -504 |
| 6 | 5268 |
| 7 | -33960 |
| 8 | 286872 |
| 9 | -2089656 |
| 10 | 16524528 |
| 11 | -124872576 |
| 12 | 967652400 |
| 13 | -7394858496 |
| 14 | 56948789280 |
| 15 | -436704535776 |
| 16 | 3356724764544 |
| 17 | -25767744878592 |
| 18 | 197948016193344 |
| 19 | -1520029557845376 |
| 20 | 11674792161026688 |
| 21 | -89658816678161280 |
| 22 | 688598927703310080 |
[1,0,6,-6,120,-504,5268,-33960,286872,-2089656, 16524528,-124872576,967652400,-7394858496, 56948789280,-436704535776,3356724764544, -25767744878592,197948016193344,-1520029557845376, 11674792161026688,-89658816678161280, 688598927703310080] |