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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 12 |
| 6 | 26 |
| 7 | 90 |
| 8 | 200 |
| 9 | 665 |
| 10 | 3980 |
| 11 | 10515 |
| 12 | 52518 |
| 13 | 433447 |
| 14 | 1973317 |
| 15 | 14252749 |
| 16 | 166762668 |
| 17 | 1065468116 |
| 18 | 11148385916 |
| 19 | 193707228525 |
| 20 | 1758897674635 |
| 21 | 26740845738267 |
| 22 | 672553810724428 |
| 23 | 9032785397690122 |
| 24 | 199494539604910376 |
[1,3,1,2,6,12,26,90,200,665,3980,10515,52518, 433447,1973317,14252749,166762668,1065468116, 11148385916,193707228525,1758897674635, 26740845738267,672553810724428,9032785397690122, 199494539604910376] |