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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 9 |
| 2 | 57 |
| 3 | 401 |
| 4 | 2801 |
| 5 | 19609 |
| 6 | 137257 |
| 7 | 960801 |
| 8 | 6725601 |
| 9 | 47079209 |
| 10 | 329554457 |
| 11 | 2306881201 |
| 12 | 16148168401 |
| 13 | 113037178809 |
| 14 | 791260251657 |
| 15 | 5538821761601 |
| 16 | 38771752331201 |
| 17 | 271402266318409 |
| 18 | 1899815864228857 |
| 19 | 13298711049602001 |
| 20 | 93090977347214001 |
| 21 | 651636841430498009 |
[1,9,57,401,2801,19609,137257,960801,6725601, 47079209,329554457,2306881201,16148168401, 113037178809,791260251657,5538821761601, 38771752331201,271402266318409,1899815864228857, 13298711049602001,93090977347214001, 651636841430498009] |