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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 35 |
| 3 | 240 |
| 4 | 1650 |
| 5 | 11340 |
| 6 | 77940 |
| 7 | 535680 |
| 8 | 3681720 |
| 9 | 25304400 |
| 10 | 173916720 |
| 11 | 1195326720 |
| 12 | 8215460640 |
| 13 | 56464724160 |
| 14 | 388081108800 |
| 15 | 2667274997760 |
| 16 | 18332136639360 |
| 17 | 125996469822720 |
| 18 | 865971638772480 |
| 19 | 5951808651571200 |
[1,5,35,240,1650,11340,77940,535680,3681720, 25304400,173916720,1195326720,8215460640, 56464724160,388081108800,2667274997760, 18332136639360,125996469822720,865971638772480, 5951808651571200] |