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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 9 |
| 2 | 49 |
| 3 | 99 |
| 4 | 499 |
| 5 | 999 |
| 6 | 4999 |
| 7 | 9999 |
| 8 | 49999 |
| 9 | 99999 |
| 10 | 499999 |
| 11 | 999999 |
| 12 | 4999999 |
| 13 | 9999999 |
| 14 | 49999999 |
| 15 | 99999999 |
| 16 | 499999999 |
| 17 | 999999999 |
| 18 | 4999999999 |
| 19 | 9999999999 |
| 20 | 49999999999 |
| 21 | 99999999999 |
| 22 | 499999999999 |
| 23 | 999999999999 |
| 24 | 4999999999999 |
| 25 | 9999999999999 |
| 26 | 49999999999999 |
[4,9,49,99,499,999,4999,9999,49999,99999,499999, 999999,4999999,9999999,49999999,99999999, 499999999,999999999,4999999999,9999999999, 49999999999,99999999999,499999999999,999999999999, 4999999999999,9999999999999,49999999999999] |