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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 0 |
| 5 | -15 |
| 6 | 90 |
| 7 | 273 |
| 8 | -2520 |
| 9 | -375 |
| 10 | 126630 |
| 11 | -269907 |
| 12 | -7232940 |
| 13 | 44118165 |
| 14 | 525494970 |
| 15 | -6182721087 |
| 16 | -41497943760 |
| 17 | 965945373105 |
| 18 | 2901128941710 |
| 19 | -171088458444267 |
| 20 | 81569169583020 |
| 21 | 34527329266886445 |
[1,0,0,3,0,-15,90,273,-2520,-375,126630,-269907, -7232940,44118165,525494970,-6182721087, -41497943760,965945373105,2901128941710, -171088458444267,81569169583020,34527329266886445] |