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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 40 |
| 2 | 760 |
| 3 | 9120 |
| 4 | 77560 |
| 5 | 1546224 |
| 6 | 2508000 |
| 7 | 31204160 |
| 8 | 34729720 |
| 9 | 300136200 |
| 10 | 259114704 |
| 11 | 1823305440 |
| 12 | 1327461600 |
| 13 | 8216920880 |
| 14 | 5341699520 |
| 15 | 29758804416 |
| 16 | 17701924600 |
| 17 | 91800254160 |
| 18 | 51294999960 |
| 19 | 249835104800 |
| 20 | 131880275664 |
| 21 | 614963569920 |
| 22 | 312126610080 |
| 23 | 1394448792000 |
[1,40,760,9120,77560,1546224,2508000,31204160, 34729720,300136200,259114704,1823305440, 1327461600,8216920880,5341699520,29758804416, 17701924600,91800254160,51294999960,249835104800, 131880275664,614963569920,312126610080, 1394448792000] |