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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 225 |
| 5 | 3224 |
| 6 | 29274 |
| 7 | 215900 |
| 8 | 1412275 |
| 9 | 8541876 |
| 10 | 48876212 |
| 11 | 268288008 |
| 12 | 1425694725 |
| 13 | 7381073920 |
| 14 | 37399844174 |
| 15 | 186110137668 |
| 16 | 911952794935 |
| 17 | 4409472232060 |
| 18 | 21073909951080 |
| 19 | 99688911645264 |
| 20 | 467292120940425 |
[0,0,0,225,3224,29274,215900,1412275,8541876, 48876212,268288008,1425694725,7381073920, 37399844174,186110137668,911952794935, 4409472232060,21073909951080,99688911645264, 467292120940425] |