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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 6 |
| 6 | 28 |
| 7 | 252 |
| 8 | 4726 |
| 9 | 150324 |
| 10 | 8308928 |
| 11 | 817860888 |
| 12 | 144938364368 |
| 13 | 46784208920560 |
| 14 | 27789645300385184 |
| 15 | 30630702203393521120 |
| 16 | 63070163901389334212336 |
| 17 | 243902725979609232729020320 |
| 18 | 1779250465648201682685291759744 |
[1,0,0,1,6,28,252,4726,150324,8308928,817860888, 144938364368,46784208920560,27789645300385184, 30630702203393521120,63070163901389334212336, 243902725979609232729020320, 1779250465648201682685291759744] |