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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 255 |
| 3 | 518320 |
| 4 | 4041974015 |
| 5 | 85800824609376 |
| 6 | 4051316109991426752 |
| 7 | 372271852759802667094256 |
| 8 | 60525940157456181486116315391 |
| 9 | 16213293097463939456656505907266320 |
[1,255,518320,4041974015,85800824609376, 4051316109991426752,372271852759802667094256, 60525940157456181486116315391, 16213293097463939456656505907266320] |