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| n | a(n) |
|---|---|
| 3 | 0 |
| 4 | 3 |
| 5 | 30 |
| 6 | 210 |
| 7 | 1260 |
| 8 | 6944 |
| 9 | 36288 |
| 10 | 182880 |
| 11 | 897600 |
| 12 | 4316928 |
| 13 | 20427264 |
| 14 | 95373824 |
| 15 | 440294400 |
| 16 | 2013020160 |
| 17 | 9126248448 |
| 18 | 41069371392 |
| 19 | 183607050240 |
| 20 | 816037560320 |
| 21 | 3607758766080 |
| 22 | 15874168848384 |
| 23 | 69544044134400 |
| 24 | 303465064562688 |
[0,3,30,210,1260,6944,36288,182880,897600,4316928, 20427264,95373824,440294400,2013020160,9126248448, 41069371392,183607050240,816037560320, 3607758766080,15874168848384,69544044134400, 303465064562688] |