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| n | a(n) |
|---|---|
| 1 | 7 |
| 2 | 77 |
| 3 | 777 |
| 4 | 7777 |
| 5 | 77777 |
| 6 | 777777 |
| 7 | 3999999 |
| 8 | 4688999 |
| 9 | 4689899 |
| 10 | 4689989 |
| 11 | 4689998 |
| 12 | 4698899 |
| 13 | 4698989 |
| 14 | 4698998 |
| 15 | 4699889 |
| 16 | 4699898 |
| 17 | 4699988 |
| 18 | 4868999 |
| 19 | 4869899 |
| 20 | 4869989 |
| 21 | 4869998 |
| 22 | 4886999 |
| 23 | 4888888 |
| 24 | 4889699 |
| 25 | 4889969 |
| 26 | 4889996 |
| 27 | 4896899 |
[7,77,777,7777,77777,777777,3999999,4688999, 4689899,4689989,4689998,4698899,4698989,4698998, 4699889,4699898,4699988,4868999,4869899,4869989, 4869998,4886999,4888888,4889699,4889969,4889996, 4896899] |