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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 63 |
| 4 | 469 |
| 5 | 4025 |
| 6 | 31031 |
| 7 | 259287 |
| 8 | 2039093 |
| 9 | 16783249 |
| 10 | 133482055 |
| 11 | 1089343311 |
| 12 | 8719307317 |
| 13 | 70816436873 |
| 14 | 568878932279 |
| 15 | 4607763271335 |
| 16 | 37090594224341 |
| 17 | 299961588744097 |
| 18 | 2417362294480903 |
| 19 | 19532842437422559 |
| 20 | 157516437304409365 |
[1,7,63,469,4025,31031,259287,2039093,16783249, 133482055,1089343311,8719307317,70816436873, 568878932279,4607763271335,37090594224341, 299961588744097,2417362294480903, 19532842437422559,157516437304409365] |