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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | -1 |
| 3 | 3 |
| 4 | -6 |
| 5 | 23 |
| 6 | -90 |
| 7 | 91 |
| 8 | 2520 |
| 9 | -37549 |
| 10 | 461160 |
| 11 | -5366339 |
| 12 | 58528008 |
| 13 | -607263295 |
| 14 | 5930324400 |
| 15 | -49004509553 |
| 16 | 192095423520 |
| 17 | 4873161825335 |
| 18 | -189700932165696 |
| 19 | 4680846631063441 |
| 20 | -99367558621150840 |
| 21 | 1935131558912511581 |
[0,0,-1,3,-6,23,-90,91,2520,-37549,461160, -5366339,58528008,-607263295,5930324400, -49004509553,192095423520,4873161825335, -189700932165696,4680846631063441, -99367558621150840,1935131558912511581] |