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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 48 |
| 3 | 960 |
| 4 | 26880 |
| 5 | 967680 |
| 6 | 42577920 |
| 7 | 2214051840 |
| 8 | 132843110400 |
| 9 | 9033331507200 |
| 10 | 686533194547200 |
| 11 | 57668788341964800 |
| 12 | 5305528527460761600 |
| 13 | 530552852746076160000 |
| 14 | 57299708096576225280000 |
| 15 | 6646766139202842132480000 |
| 16 | 824199001261152424427520000 |
| 17 | 108794268166472120024432640000 |
[1,4,48,960,26880,967680,42577920,2214051840, 132843110400,9033331507200,686533194547200, 57668788341964800,5305528527460761600, 530552852746076160000,57299708096576225280000, 6646766139202842132480000, 824199001261152424427520000, 108794268166472120024432640000] |