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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 47 |
| 3 | 420 |
| 4 | 4058 |
| 5 | 41286 |
| 6 | 435739 |
| 7 | 4726644 |
| 8 | 52373294 |
| 9 | 590247900 |
| 10 | 6744908118 |
| 11 | 77969430864 |
| 12 | 910131055980 |
| 13 | 10712886629958 |
| 14 | 127012431301779 |
| 15 | 1515405441505380 |
| 16 | 18181513435560278 |
| 17 | 219219809605566132 |
| 18 | 2654917102081791394 |
| 19 | 32281268283914386200 |
[1,6,47,420,4058,41286,435739,4726644,52373294, 590247900,6744908118,77969430864,910131055980, 10712886629958,127012431301779,1515405441505380, 18181513435560278,219219809605566132, 2654917102081791394,32281268283914386200] |