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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 864 |
| 4 | 17915904 |
| 5 | 57330892800000 |
| 6 | 41794220851200000000000 |
| 7 | 9635211808655307020697600000000000 |
| 8 | 931891782579353562478377930946353561600000000000 |
| 9 | 48457159197906991133853954271145046614004301737177907200000000000 |
[1,4,864,17915904,57330892800000, 41794220851200000000000, 9635211808655307020697600000000000, 931891782579353562478377930946353561600000000000, 48457159197906991133853954271145046614004301737177\ 907200000000000] |