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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -20 |
| 2 | 170 |
| 3 | -800 |
| 4 | 2415 |
| 5 | -6404 |
| 6 | 21550 |
| 7 | -71080 |
| 8 | 178295 |
| 9 | -419200 |
| 10 | 1203282 |
| 11 | -3294360 |
| 12 | 7476320 |
| 13 | -17381780 |
| 14 | 44919500 |
| 15 | -107605880 |
| 16 | 237628435 |
| 17 | -544086720 |
| 18 | 1273805460 |
| 19 | -2864694880 |
| 20 | 6256648862 |
| 21 | -13710129840 |
[1,-20,170,-800,2415,-6404,21550,-71080,178295, -419200,1203282,-3294360,7476320,-17381780, 44919500,-107605880,237628435,-544086720, 1273805460,-2864694880,6256648862,-13710129840] |