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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 6 |
| 5 | 8 |
| 6 | 118 |
| 7 | 880 |
| 8 | 14400 |
| 9 | 318220 |
| 10 | 10446298 |
| 11 | 531060152 |
| 12 | 39577654480 |
| 13 | 4465022457276 |
| 14 | 757302604610482 |
| 15 | 191605833481050984 |
[0,1,0,6,8,118,880,14400,318220,10446298, 531060152,39577654480,4465022457276, 757302604610482,191605833481050984] |