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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 48 |
| 5 | 248 |
| 6 | 1504 |
| 7 | 10560 |
| 8 | 84544 |
| 9 | 761024 |
| 10 | 7610496 |
| 11 | 83715968 |
| 12 | 1004592640 |
| 13 | 13059706368 |
| 14 | 182835893248 |
| 15 | 2742538406912 |
| 16 | 43880614526976 |
| 17 | 745970446991360 |
| 18 | 13427468045910016 |
| 19 | 255121892872421376 |
| 20 | 5102437857448689664 |
| 21 | 107151195006423007232 |
| 22 | 2357326290141307207680 |
[0,1,3,11,48,248,1504,10560,84544,761024,7610496, 83715968,1004592640,13059706368,182835893248, 2742538406912,43880614526976,745970446991360, 13427468045910016,255121892872421376, 5102437857448689664,107151195006423007232, 2357326290141307207680] |