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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 44 |
| 3 | 544 |
| 4 | 4544 |
| 5 | 44544 |
| 6 | 444544 |
| 7 | 4444544 |
| 8 | 54444544 |
| 9 | 454444544 |
| 10 | 5454444544 |
| 11 | 45454444544 |
| 12 | 545454444544 |
| 13 | 5545454444544 |
| 14 | 55545454444544 |
| 15 | 555545454444544 |
| 16 | 4555545454444544 |
| 17 | 44555545454444544 |
| 18 | 544555545454444544 |
[4,44,544,4544,44544,444544,4444544,54444544, 454444544,5454444544,45454444544,545454444544, 5545454444544,55545454444544,555545454444544, 4555545454444544,44555545454444544, 544555545454444544] |