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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 0 |
| 4 | -8 |
| 5 | 12 |
| 6 | 168 |
| 7 | -280 |
| 8 | -5760 |
| 9 | 11536 |
| 10 | 310304 |
| 11 | -703296 |
| 12 | -23894144 |
| 13 | 59653440 |
| 14 | 2481859968 |
| 15 | -6715007104 |
| 16 | -333725331456 |
| 17 | 967972497664 |
| 18 | 56329065984512 |
| 19 | -173764741920768 |
| 20 | -11650274400684032 |
| 21 | 37986612815698944 |
[0,1,2,0,-8,12,168,-280,-5760,11536,310304, -703296,-23894144,59653440,2481859968,-6715007104, -333725331456,967972497664,56329065984512, -173764741920768,-11650274400684032, 37986612815698944] |