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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 51 |
| 4 | 906 |
| 5 | 24690 |
| 6 | 956790 |
| 7 | 49993650 |
| 8 | 3387124440 |
| 9 | 288755250840 |
| 10 | 30247310482200 |
| 11 | 3818739956308200 |
| 12 | 571858101118458000 |
| 13 | 100218359688123877200 |
| 14 | 20319306632495415745200 |
| 15 | 4719164981053010642154000 |
| 16 | 1244680987088062472732784000 |
| 17 | 369981708267221405777101680000 |
[1,1,5,51,906,24690,956790,49993650,3387124440, 288755250840,30247310482200,3818739956308200, 571858101118458000,100218359688123877200, 20319306632495415745200,4719164981053010642154000, 1244680987088062472732784000, 369981708267221405777101680000] |