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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 20 |
| 3 | 300 |
| 4 | 9980 |
| 5 | 616260 |
| 6 | 65814020 |
| 7 | 11878194300 |
| 8 | 3621432947180 |
| 9 | 1880516646144660 |
| 10 | 1678121372919602420 |
| 11 | 2590609089652498130700 |
| 12 | 6947580541943715645962780 |
| 13 | 32448510765823652400410879460 |
| 14 | 264301377639329321236008592510820 |
[1,5,20,300,9980,616260,65814020,11878194300, 3621432947180,1880516646144660, 1678121372919602420,2590609089652498130700, 6947580541943715645962780, 32448510765823652400410879460, 264301377639329321236008592510820] |