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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -2 |
| 3 | 6 |
| 4 | -26 |
| 5 | 180 |
| 6 | -1734 |
| 7 | 23464 |
| 8 | -385160 |
| 9 | 7561308 |
| 10 | -166580820 |
| 11 | 4109707800 |
| 12 | -110972371608 |
| 13 | 3276276647280 |
| 14 | -104668338898200 |
| 15 | 3609072471039840 |
| 16 | -133458102348679680 |
| 17 | 5274992059017870048 |
| 18 | -221831508056339323584 |
| 19 | 9893765935654872310656 |
| 20 | -466361328442205843665920 |
[0,1,-2,6,-26,180,-1734,23464,-385160,7561308, -166580820,4109707800,-110972371608,3276276647280, -104668338898200,3609072471039840, -133458102348679680,5274992059017870048, -221831508056339323584,9893765935654872310656, -466361328442205843665920] |