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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 11 |
| 4 | 73 |
| 5 | 516 |
| 6 | 3825 |
| 7 | 29344 |
| 8 | 231050 |
| 9 | 1856679 |
| 10 | 15166101 |
| 11 | 125557710 |
| 12 | 1051197507 |
| 13 | 8884941534 |
| 14 | 75712772251 |
| 15 | 649768843803 |
| 16 | 5611020122345 |
| 17 | 48719510621895 |
| 18 | 425088400156118 |
| 19 | 3725196584960963 |
| 20 | 32773601544458209 |
| 21 | 289362605686184615 |
| 22 | 2563091445861948236 |
[1,0,2,11,73,516,3825,29344,231050,1856679, 15166101,125557710,1051197507,8884941534, 75712772251,649768843803,5611020122345, 48719510621895,425088400156118,3725196584960963, 32773601544458209,289362605686184615, 2563091445861948236] |