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| n | a(n) |
|---|---|
| 1 | 9 |
| 2 | 81 |
| 3 | 441 |
| 4 | 2601 |
| 5 | 15129 |
| 6 | 88209 |
| 7 | 514089 |
| 8 | 2996361 |
| 9 | 17464041 |
| 10 | 101787921 |
| 11 | 593263449 |
| 12 | 3457792809 |
| 13 | 20153493369 |
| 14 | 117463167441 |
| 15 | 684625511241 |
| 16 | 3990289900041 |
| 17 | 23257113888969 |
| 18 | 135552393433809 |
| 19 | 790057246713849 |
| 20 | 4604791086849321 |
[9,81,441,2601,15129,88209,514089,2996361, 17464041,101787921,593263449,3457792809, 20153493369,117463167441,684625511241, 3990289900041,23257113888969,135552393433809, 790057246713849,4604791086849321] |