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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 32 |
| 2 | 200 |
| 3 | 1120 |
| 4 | 5880 |
| 5 | 29568 |
| 6 | 144144 |
| 7 | 686400 |
| 8 | 3208920 |
| 9 | 14780480 |
| 10 | 67251184 |
| 11 | 302865472 |
| 12 | 1352078000 |
| 13 | 5990745600 |
| 14 | 26369978400 |
| 15 | 115407434880 |
| 16 | 502503206040 |
| 17 | 2178032472000 |
| 18 | 9401840170800 |
| 19 | 40434981787200 |
| 20 | 173319035569680 |
| 21 | 740642835229440 |
| 22 | 3156148445580000 |
[4,32,200,1120,5880,29568,144144,686400,3208920, 14780480,67251184,302865472,1352078000,5990745600, 26369978400,115407434880,502503206040, 2178032472000,9401840170800,40434981787200, 173319035569680,740642835229440,3156148445580000] |