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| n | a(n) |
|---|---|
| 1 | 20 |
| 2 | 16260 |
| 3 | 16214000 |
| 4 | 20982583300 |
| 5 | 31091880269520 |
| 6 | 50432680389260400 |
| 7 | 87186713382942888000 |
| 8 | 158040497103890978362500 |
| 9 | 297155971199028097720850000 |
| 10 | 575241665325478123466841078160 |
[20,16260,16214000,20982583300,31091880269520, 50432680389260400,87186713382942888000, 158040497103890978362500, 297155971199028097720850000, 575241665325478123466841078160] |