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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 42 |
| 3 | 294 |
| 4 | 2058 |
| 5 | 14406 |
| 6 | 100842 |
| 7 | 705894 |
| 8 | 4941258 |
| 9 | 34588806 |
| 10 | 242121642 |
| 11 | 1694851494 |
| 12 | 11863960458 |
| 13 | 83047723206 |
| 14 | 581334062442 |
| 15 | 4069338437094 |
| 16 | 28485369059658 |
| 17 | 199397583417606 |
| 18 | 1395783083923242 |
| 19 | 9770481587462694 |
[1,6,42,294,2058,14406,100842,705894,4941258, 34588806,242121642,1694851494,11863960458, 83047723206,581334062442,4069338437094, 28485369059658,199397583417606,1395783083923242, 9770481587462694] |