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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -20 |
| 2 | 190 |
| 3 | -1160 |
| 4 | 5245 |
| 5 | -19324 |
| 6 | 62150 |
| 7 | -182040 |
| 8 | 495750 |
| 9 | -1269620 |
| 10 | 3088376 |
| 11 | -7197240 |
| 12 | 16164595 |
| 13 | -35136760 |
| 14 | 74192590 |
| 15 | -152674048 |
| 16 | 306968470 |
| 17 | -604298520 |
| 18 | 1166898210 |
| 19 | -2213813640 |
| 20 | 4132159452 |
| 21 | -7597272900 |
[1,-20,190,-1160,5245,-19324,62150,-182040,495750, -1269620,3088376,-7197240,16164595,-35136760, 74192590,-152674048,306968470,-604298520, 1166898210,-2213813640,4132159452,-7597272900] |