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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 21 |
| 2 | 289 |
| 3 | 3333 |
| 4 | 35073 |
| 5 | 350005 |
| 6 | 3379489 |
| 7 | 31933221 |
| 8 | 297326337 |
| 9 | 2739788117 |
| 10 | 25057889313 |
| 11 | 227913373253 |
| 12 | 2064391824897 |
| 13 | 18639827016309 |
| 14 | 167893750058529 |
| 15 | 1509403565177445 |
| 16 | 13549789700813313 |
| 17 | 121493423266590357 |
| 18 | 1088358864961303329 |
| 19 | 9742576323085181829 |
| 20 | 87161303214793783041 |
[1,21,289,3333,35073,350005,3379489,31933221, 297326337,2739788117,25057889313,227913373253, 2064391824897,18639827016309,167893750058529, 1509403565177445,13549789700813313, 121493423266590357,1088358864961303329, 9742576323085181829,87161303214793783041] |