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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 40 |
| 4 | 485 |
| 5 | 7776 |
| 6 | 156457 |
| 7 | 3788800 |
| 8 | 107414505 |
| 9 | 3491200000 |
| 10 | 128019454541 |
| 11 | 5229222395904 |
| 12 | 235490648957005 |
| 13 | 11592449531084800 |
| 14 | 619331166211640625 |
| 15 | 35691050995648823296 |
| 16 | 2206955604752999720273 |
| 17 | 145757527499874820423680 |
| 18 | 10240455593560436925898645 |
[1,1,5,40,485,7776,156457,3788800,107414505, 3491200000,128019454541,5229222395904, 235490648957005,11592449531084800, 619331166211640625,35691050995648823296, 2206955604752999720273,145757527499874820423680, 10240455593560436925898645] |