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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 21 |
| 3 | 180 |
| 4 | 1225 |
| 5 | 9820 |
| 6 | 90785 |
| 7 | 841164 |
| 8 | 7551453 |
| 9 | 69952442 |
| 10 | 680669118 |
| 11 | 6633057660 |
| 12 | 63951722552 |
| 13 | 623631395787 |
| 14 | 6183296733749 |
| 15 | 61331317468332 |
| 16 | 606202380764411 |
| 17 | 6014248065257267 |
| 18 | 59984150594548551 |
| 19 | 598328234748009180 |
[2,21,180,1225,9820,90785,841164,7551453,69952442, 680669118,6633057660,63951722552,623631395787, 6183296733749,61331317468332,606202380764411, 6014248065257267,59984150594548551, 598328234748009180] |