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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 11 |
| 4 | 71 |
| 5 | 705 |
| 6 | 8470 |
| 7 | 127284 |
| 8 | 2231342 |
| 9 | 45505041 |
| 10 | 1048341387 |
| 11 | 27059612615 |
| 12 | 771505041184 |
| 13 | 24109351520196 |
| 14 | 818862556900962 |
| 15 | 30044548635160841 |
| 16 | 1184027932446520895 |
| 17 | 49883835880381353808 |
| 18 | 2237276988838875420087 |
[1,1,2,11,71,705,8470,127284,2231342,45505041, 1048341387,27059612615,771505041184, 24109351520196,818862556900962,30044548635160841, 1184027932446520895,49883835880381353808, 2237276988838875420087] |