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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 30 |
| 4 | 0 |
| 5 | 360 |
| 6 | 7650 |
| 7 | 0 |
| 8 | 302400 |
| 9 | 4544400 |
| 10 | 11226600 |
| 11 | 324324000 |
| 12 | 4310633250 |
| 13 | 24324300000 |
| 14 | 437404968000 |
| 15 | 5634178329780 |
| 16 | 45972927000000 |
| 17 | 697866761592000 |
| 18 | 8962716395833200 |
| 19 | 88725951057744000 |
| 20 | 1258898645656852200 |
[1,0,0,30,0,360,7650,0,302400,4544400,11226600, 324324000,4310633250,24324300000,437404968000, 5634178329780,45972927000000,697866761592000, 8962716395833200,88725951057744000, 1258898645656852200] |