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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 6 |
| 7 | 42 |
| 8 | 336 |
| 9 | 3024 |
| 10 | 30366 |
| 11 | 335412 |
| 12 | 4041576 |
| 13 | 52756704 |
| 14 | 741620880 |
| 15 | 11169844686 |
| 16 | 179448036768 |
| 17 | 3063069801792 |
| 18 | 55360031126400 |
| 19 | 1056123043335360 |
| 20 | 21208345049147256 |
| 21 | 447183762148547424 |
| 22 | 9877939209960101280 |
| 23 | 228112734232663600320 |
[1,0,0,0,0,1,6,42,336,3024,30366,335412,4041576, 52756704,741620880,11169844686,179448036768, 3063069801792,55360031126400,1056123043335360, 21208345049147256,447183762148547424, 9877939209960101280,228112734232663600320] |