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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 5 |
| 5 | 24 |
| 6 | 136 |
| 7 | 879 |
| 8 | 6554 |
| 9 | 55412 |
| 10 | 523897 |
| 11 | 5477110 |
| 12 | 62737806 |
| 13 | 781370863 |
| 14 | 10512989797 |
| 15 | 151960488890 |
| 16 | 2348480282846 |
| 17 | 38643175563195 |
| 18 | 674499064375771 |
| 19 | 12447573642571060 |
| 20 | 242161887228200639 |
| 21 | 4953311329667740358 |
[1,0,0,1,5,24,136,879,6554,55412,523897,5477110, 62737806,781370863,10512989797,151960488890, 2348480282846,38643175563195,674499064375771, 12447573642571060,242161887228200639, 4953311329667740358] |