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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 43 |
| 4 | 289 |
| 5 | 2239 |
| 6 | 19699 |
| 7 | 192025 |
| 8 | 2042971 |
| 9 | 23520715 |
| 10 | 291099349 |
| 11 | 3849621019 |
| 12 | 54110928355 |
| 13 | 804827487493 |
| 14 | 12619011606775 |
| 15 | 207885167529523 |
| 16 | 3587864566792753 |
| 17 | 64705561315720135 |
| 18 | 1216574535057705979 |
| 19 | 23797327657083197113 |
| 20 | 483390249416359706995 |
[1,1,7,43,289,2239,19699,192025,2042971,23520715, 291099349,3849621019,54110928355,804827487493, 12619011606775,207885167529523,3587864566792753, 64705561315720135,1216574535057705979, 23797327657083197113,483390249416359706995] |