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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 7 |
| 3 | 77 |
| 4 | 777 |
| 5 | 7777 |
| 6 | 77777 |
| 7 | 111111 |
| 8 | 222222 |
| 9 | 333333 |
| 10 | 444444 |
| 11 | 555555 |
| 12 | 666666 |
| 13 | 777777 |
| 14 | 888888 |
| 15 | 999999 |
| 16 | 7777777 |
| 17 | 77777777 |
| 18 | 777777777 |
| 19 | 7777777777 |
| 20 | 77777777777 |
| 21 | 111111111111 |
| 22 | 222222222222 |
| 23 | 333333333333 |
| 24 | 444444444444 |
| 25 | 555555555555 |
| 26 | 666666666666 |
| 27 | 777777777777 |
[0,7,77,777,7777,77777,111111,222222,333333, 444444,555555,666666,777777,888888,999999,7777777, 77777777,777777777,7777777777,77777777777, 111111111111,222222222222,333333333333, 444444444444,555555555555,666666666666, 777777777777] |