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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 18 |
| 2 | 1080 |
| 3 | 109024 |
| 4 | 15425932 |
| 5 | 2807373808 |
| 6 | 624567442464 |
| 7 | 164229954020384 |
| 8 | 49830967023579400 |
| 9 | 17136446536264628328 |
| 10 | 6586556828478666923776 |
| 11 | 2798143974987211154322560 |
| 12 | 1301956008571438833028276672 |
| 13 | 658475124477897905982708920064 |
| 14 | 359674624553169582199492194921216 |
| 15 | 211016939776698518257518156591766656 |
| 16 | 132339913526099601722463496476503304848 |
| 17 | 88352431866089178236286985348733511803104 |
| 18 | 62560734523453615823978316851314371901576832 |
[1,18,1080,109024,15425932,2807373808, 624567442464,164229954020384,49830967023579400, 17136446536264628328,6586556828478666923776, 2798143974987211154322560, 1301956008571438833028276672, 658475124477897905982708920064, 359674624553169582199492194921216, 211016939776698518257518156591766656, 132339913526099601722463496476503304848, 88352431866089178236286985348733511803104, 62560734523453615823978316851314371901576832] |