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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | -20 |
| 3 | -145 |
| 4 | 355 |
| 5 | 3980 |
| 6 | -4895 |
| 7 | -104395 |
| 8 | 17980 |
| 9 | 2627855 |
| 10 | 2178355 |
| 11 | -63518020 |
| 12 | -117976895 |
| 13 | 1469973605 |
| 14 | 4419395980 |
| 15 | -32329944145 |
| 16 | -142814843645 |
| 17 | 665433759980 |
| 18 | 4235804851105 |
| 19 | -12400039148395 |
| 20 | -118295160426020 |
| 21 | 191705818283855 |
[1,5,-20,-145,355,3980,-4895,-104395,17980, 2627855,2178355,-63518020,-117976895,1469973605, 4419395980,-32329944145,-142814843645, 665433759980,4235804851105,-12400039148395, -118295160426020,191705818283855] |