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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 1152 |
| 3 | 1428840 |
| 4 | 3488808960 |
| 5 | 15044494500000 |
| 6 | 105235903511101440 |
| 7 | 1119277024472896248960 |
| 8 | 17216259547948971039129600 |
| 9 | 368066786222106315186876633600 |
| 10 | 10591209807103301277597696000000000 |
| 11 | 399472472359100444604916002033020774400 |
[0,2,1152,1428840,3488808960,15044494500000, 105235903511101440,1119277024472896248960, 17216259547948971039129600, 368066786222106315186876633600, 10591209807103301277597696000000000, 399472472359100444604916002033020774400] |