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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 20 |
| 5 | 195 |
| 6 | 1430 |
| 7 | 9009 |
| 8 | 51688 |
| 9 | 278460 |
| 10 | 1434120 |
| 11 | 7141530 |
| 12 | 34648856 |
| 13 | 164663785 |
| 14 | 769491450 |
| 15 | 3546222225 |
| 16 | 16152872400 |
| 17 | 72846725160 |
| 18 | 325722299760 |
| 19 | 1445598337950 |
| 20 | 6373942543800 |
| 21 | 27942072562950 |
| 22 | 121863923024844 |
| 23 | 529043313674106 |
| 24 | 2287209524819120 |
[0,0,0,1,20,195,1430,9009,51688,278460,1434120, 7141530,34648856,164663785,769491450,3546222225, 16152872400,72846725160,325722299760, 1445598337950,6373942543800,27942072562950, 121863923024844,529043313674106,2287209524819120] |