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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 756 |
| 3 | 5760 |
| 4 | 98928 |
| 5 | 1092096 |
| 6 | 8435760 |
| 7 | 45142272 |
| 8 | 202712400 |
| 9 | 715373568 |
| 10 | 2350118808 |
| 11 | 6501914496 |
| 12 | 17469036096 |
| 13 | 40850459136 |
| 14 | 95266994400 |
| 15 | 197161655040 |
| 16 | 413591044176 |
| 17 | 781142621184 |
| 18 | 1511741623812 |
| 19 | 2655160539264 |
| 20 | 4815051144480 |
| 21 | 7984019699712 |
| 22 | 13744582363152 |
[1,0,756,5760,98928,1092096,8435760,45142272, 202712400,715373568,2350118808,6501914496, 17469036096,40850459136,95266994400,197161655040, 413591044176,781142621184,1511741623812, 2655160539264,4815051144480,7984019699712, 13744582363152] |