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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 71 |
| 3 | 478 |
| 4 | 3248 |
| 5 | 19674 |
| 6 | 116885 |
| 7 | 655064 |
| 8 | 3602627 |
| 9 | 19082622 |
| 10 | 99353815 |
| 11 | 503974610 |
| 12 | 2518347829 |
| 13 | 12341129010 |
| 14 | 59691674707 |
| 15 | 284343349874 |
| 16 | 1339171125620 |
| 17 | 6229010760982 |
| 18 | 28686750790598 |
| 19 | 130740792179088 |
| 20 | 590661906472634 |
| 21 | 2644740541614160 |
[1,8,71,478,3248,19674,116885,655064,3602627, 19082622,99353815,503974610,2518347829, 12341129010,59691674707,284343349874, 1339171125620,6229010760982,28686750790598, 130740792179088,590661906472634,2644740541614160] |