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| n | a(n) |
|---|---|
| 10 | 1 |
| 11 | 0 |
| 12 | 2 |
| 13 | 4 |
| 14 | 23 |
| 15 | 149 |
| 16 | 1670 |
| 17 | 23882 |
| 18 | 422194 |
| 19 | 8544496 |
| 20 | 195291551 |
[1,0,2,4,23,149,1670,23882,422194,8544496, 195291551] |