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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 20 |
| 5 | 78 |
| 6 | 2459 |
| 7 | 14028740 |
| 8 | 29284932080025185 |
| 9 | 468863491068204454517854447175206 |
| 10 | 1994324729204021501147398087008429477142243091610827370319897909501551 |
[1,2,4,8,20,78,2459,14028740,29284932080025185, 468863491068204454517854447175206, 19943247292040215011473980870084294771422430916108\ 27370319897909501551] |