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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | -1 |
| 3 | 0 |
| 4 | -6 |
| 5 | 8 |
| 6 | -105 |
| 7 | 448 |
| 8 | -3780 |
| 9 | 29360 |
| 10 | -231525 |
| 11 | 2498848 |
| 12 | -20985426 |
| 13 | 271494104 |
| 14 | -2503393893 |
| 15 | 35568205216 |
| 16 | -346194368520 |
| 17 | 4969746747488 |
| 18 | -41862411119529 |
| 19 | 433992302190016 |
| 20 | 4063211694577570 |
| 21 | -232678981367758168 |
[0,0,-1,0,-6,8,-105,448,-3780,29360,-231525, 2498848,-20985426,271494104,-2503393893, 35568205216,-346194368520,4969746747488, -41862411119529,433992302190016,4063211694577570, -232678981367758168] |