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| n | a(n) |
|---|---|
| 4 | -8 |
| 5 | 200 |
| 6 | 3360 |
| 7 | 43680 |
| 8 | 551040 |
| 9 | 7136640 |
| 10 | 96768000 |
| 11 | 1383782400 |
| 12 | 20916403200 |
| 13 | 334183449600 |
| 14 | 5637529497600 |
| 15 | 100255034880000 |
| 16 | 1876076826624000 |
| 17 | 36872930045952000 |
| 18 | 759748346413056000 |
| 19 | 16381540188389376000 |
| 20 | 368990137906790400000 |
| 21 | 8668429855133368320000 |
[-8,200,3360,43680,551040,7136640,96768000, 1383782400,20916403200,334183449600,5637529497600, 100255034880000,1876076826624000, 36872930045952000,759748346413056000, 16381540188389376000,368990137906790400000, 8668429855133368320000] |