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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 8 |
| 5 | 40 |
| 6 | 200 |
| 7 | 980 |
| 8 | 5152 |
| 9 | 28448 |
| 10 | 162080 |
| 11 | 979000 |
| 12 | 6179360 |
| 13 | 40575392 |
| 14 | 279199648 |
| 15 | 1997406320 |
| 16 | 14825619200 |
| 17 | 114365751040 |
| 18 | 912510870272 |
| 19 | 7521873125408 |
| 20 | 64045101880960 |
| 21 | 561615674345600 |
| 22 | 5067769601121920 |
| 23 | 47023128008540992 |
| 24 | 447820056115824128 |
[0,0,0,2,8,40,200,980,5152,28448,162080,979000, 6179360,40575392,279199648,1997406320,14825619200, 114365751040,912510870272,7521873125408, 64045101880960,561615674345600,5067769601121920, 47023128008540992,447820056115824128] |