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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 5 |
| 4 | 13 |
| 5 | 105 |
| 6 | 576 |
| 7 | 4005 |
| 8 | 27000 |
| 9 | 193193 |
| 10 | 1402672 |
| 11 | 10433709 |
| 12 | 78807785 |
| 13 | 603996745 |
| 14 | 4683970032 |
| 15 | 36702939429 |
| 16 | 290184446349 |
| 17 | 2312460578025 |
| 18 | 18556825469040 |
| 19 | 149842592021997 |
| 20 | 1216719520281045 |
| 21 | 9929612901775761 |
| 22 | 81406058258856240 |
[1,0,5,13,105,576,4005,27000,193193,1402672, 10433709,78807785,603996745,4683970032, 36702939429,290184446349,2312460578025, 18556825469040,149842592021997,1216719520281045, 9929612901775761,81406058258856240] |