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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 20 |
| 3 | 9108 |
| 4 | 153675648 |
| 5 | 153926018668800 |
| 6 | 13624548214772203315200 |
| 7 | 148312029363286484759480524800000 |
| 8 | 262925014428462931164318003384701335633920000 |
| 9 | 96950311125839455466119755365478799838570665250861875200000 |
[1,1,20,9108,153675648,153926018668800, 13624548214772203315200, 148312029363286484759480524800000, 262925014428462931164318003384701335633920000, 96950311125839455466119755365478799838570665250861\ 875200000] |