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| n | a(n) |
|---|---|
| 0 | 20 |
| 1 | 81 |
| 2 | 3260 |
| 3 | 13121 |
| 4 | 528100 |
| 5 | 2125521 |
| 6 | 85548940 |
| 7 | 344321281 |
| 8 | 13858400180 |
| 9 | 55777922001 |
| 10 | 2244975280220 |
| 11 | 9035679042881 |
| 12 | 363672136995460 |
| 13 | 1463724227024721 |
| 14 | 58912641217984300 |
| 15 | 237114289098961921 |
[20,81,3260,13121,528100,2125521,85548940, 344321281,13858400180,55777922001,2244975280220, 9035679042881,363672136995460,1463724227024721, 58912641217984300,237114289098961921] |