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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 49 |
| 2 | 499 |
| 3 | 4999 |
| 4 | 49999 |
| 5 | 499999 |
| 6 | 4999999 |
| 7 | 49999999 |
| 8 | 499999999 |
| 9 | 4999999999 |
| 10 | 49999999999 |
| 11 | 499999999999 |
| 12 | 4999999999999 |
| 13 | 49999999999999 |
| 14 | 499999999999999 |
| 15 | 4999999999999999 |
| 16 | 49999999999999999 |
| 17 | 499999999999999999 |
| 18 | 4999999999999999999 |
[4,49,499,4999,49999,499999,4999999,49999999, 499999999,4999999999,49999999999,499999999999, 4999999999999,49999999999999,499999999999999, 4999999999999999,49999999999999999, 499999999999999999,4999999999999999999] |