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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 7 |
| 4 | 45 |
| 5 | 291 |
| 6 | 2030 |
| 7 | 15695 |
| 8 | 135045 |
| 9 | 1287243 |
| 10 | 13495669 |
| 11 | 154516663 |
| 12 | 1919455487 |
| 13 | 25721712601 |
| 14 | 369942275033 |
[0,0,1,7,45,291,2030,15695,135045,1287243, 13495669,154516663,1919455487,25721712601, 369942275033] |