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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 32 |
| 5 | 150 |
| 6 | 1524 |
| 7 | 12600 |
| 8 | 147328 |
| 9 | 1705536 |
| 10 | 23681520 |
| 11 | 345605040 |
| 12 | 5654922624 |
| 13 | 98624766240 |
| 14 | 1870594556544 |
| 15 | 37794037488480 |
| 16 | 817362198512640 |
| 17 | 18742996919324160 |
| 18 | 455648694329309184 |
| 19 | 11683777530785978880 |
| 20 | 315505598702787118080 |
| 21 | 8943481464393674096640 |
[1,0,2,3,32,150,1524,12600,147328,1705536, 23681520,345605040,5654922624,98624766240, 1870594556544,37794037488480,817362198512640, 18742996919324160,455648694329309184, 11683777530785978880,315505598702787118080, 8943481464393674096640] |