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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 11 |
| 4 | 40 |
| 5 | 361 |
| 6 | 1952 |
| 7 | 24611 |
| 8 | 177280 |
| 9 | 2873041 |
| 10 | 25866752 |
| 11 | 512343611 |
| 12 | 5535262720 |
| 13 | 129570724921 |
| 14 | 1633165156352 |
| 15 | 44110959165011 |
| 16 | 635421069967360 |
| 17 | 19450718635716001 |
| 18 | 315212388819402752 |
| 19 | 10784052561125704811 |
[0,1,2,11,40,361,1952,24611,177280,2873041, 25866752,512343611,5535262720,129570724921, 1633165156352,44110959165011,635421069967360, 19450718635716001,315212388819402752, 10784052561125704811] |