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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 720 |
| 7 | 35280 |
| 8 | 866880 |
| 9 | 13849920 |
| 10 | 158004000 |
| 11 | 1347524640 |
| 12 | 8866186560 |
| 13 | 46496324160 |
| 14 | 201705744240 |
| 15 | 748737990000 |
| 16 | 2444976293760 |
| 17 | 7178449299840 |
| 18 | 19276199691840 |
| 19 | 47983899216960 |
| 20 | 111920569776000 |
| 21 | 246727594270080 |
| 22 | 517702915311120 |
| 23 | 1039979954779920 |
[0,0,0,0,0,0,720,35280,866880,13849920,158004000, 1347524640,8866186560,46496324160,201705744240, 748737990000,2444976293760,7178449299840, 19276199691840,47983899216960,111920569776000, 246727594270080,517702915311120,1039979954779920] |