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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | -4 |
| 3 | 6 |
| 4 | 45 |
| 5 | -300 |
| 6 | -630 |
| 7 | 18270 |
| 8 | -44415 |
| 9 | -1428840 |
| 10 | 13608000 |
| 11 | 106964550 |
| 12 | -3044747475 |
| 13 | 2748645900 |
| 14 | 674525001150 |
| 15 | -6848689097250 |
| 16 | -138141621993375 |
| 17 | 3761985048822000 |
| 18 | 12387014410270500 |
| 19 | -1765001060909336250 |
[1,0,-4,6,45,-300,-630,18270,-44415,-1428840, 13608000,106964550,-3044747475,2748645900, 674525001150,-6848689097250,-138141621993375, 3761985048822000,12387014410270500, -1765001060909336250] |