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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 4266 |
| 3 | 81792 |
| 4 | 737862 |
| 5 | 3809280 |
| 6 | 15406210 |
| 7 | 47505792 |
| 8 | 133390290 |
| 9 | 312588288 |
| 10 | 711232812 |
| 11 | 1408787328 |
| 12 | 2789963820 |
| 13 | 4931371008 |
| 14 | 8870944884 |
| 15 | 14417119872 |
| 16 | 24144502662 |
| 17 | 36878456832 |
| 18 | 58393537998 |
| 19 | 84926534016 |
[1,0,4266,81792,737862,3809280,15406210,47505792, 133390290,312588288,711232812,1408787328, 2789963820,4931371008,8870944884,14417119872, 24144502662,36878456832,58393537998,84926534016] |