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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 4 |
| 4 | 15 |
| 5 | 24 |
| 6 | 124 |
| 7 | 192 |
| 8 | 1020 |
| 9 | 1920 |
| 10 | 12264 |
| 11 | 23040 |
| 12 | 159666 |
| 13 | 322560 |
| 14 | 2555280 |
| 15 | 5041344 |
| 16 | 40893840 |
| 17 | 90744192 |
| 18 | 761260368 |
| 19 | 1814883840 |
| 20 | 15732804296 |
| 21 | 38900010240 |
| 22 | 377587663200 |
| 23 | 933600245760 |
| 24 | 9087075973248 |
| 25 | 23520702965760 |
| 26 | 254438142416640 |
[1,1,3,4,15,24,124,192,1020,1920,12264,23040, 159666,322560,2555280,5041344,40893840,90744192, 761260368,1814883840,15732804296,38900010240, 377587663200,933600245760,9087075973248, 23520702965760,254438142416640] |