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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 8 |
| 5 | 95 |
| 6 | 504 |
| 7 | 2639 |
| 8 | 7552 |
| 9 | 303831 |
| 10 | 2628800 |
| 11 | 20429629 |
| 12 | 49019904 |
| 13 | 5411290079 |
| 14 | 66517244416 |
| 15 | 731023977375 |
| 16 | 3330603843584 |
| 17 | 321415531788367 |
| 18 | 5245542324301824 |
| 19 | 79592116946574941 |
| 20 | 794502008176640000 |
[0,0,3,8,95,504,2639,7552,303831,2628800,20429629, 49019904,5411290079,66517244416,731023977375, 3330603843584,321415531788367,5245542324301824, 79592116946574941,794502008176640000] |