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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 103 |
| 6 | 518 |
| 7 | 2868 |
| 8 | 17263 |
| 9 | 111925 |
| 10 | 775994 |
| 11 | 5719338 |
| 12 | 44592007 |
| 13 | 366259499 |
| 14 | 3157877470 |
| 15 | 28492791496 |
| 16 | 268307662047 |
| 17 | 2630577754281 |
| 18 | 26795670672626 |
| 19 | 283038010150702 |
| 20 | 3094882721541239 |
| 21 | 34977231456293519 |
| 22 | 407991690851302646 |
| 23 | 4905431774834649852 |
| 24 | 60721792897771836879 |
[1,1,2,6,23,103,518,2868,17263,111925,775994, 5719338,44592007,366259499,3157877470,28492791496, 268307662047,2630577754281,26795670672626, 283038010150702,3094882721541239, 34977231456293519,407991690851302646, 4905431774834649852,60721792897771836879] |