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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 18 |
| 3 | 504 |
| 4 | 32760 |
| 5 | 4127760 |
| 6 | 895723920 |
| 7 | 308129028480 |
| 8 | 158070191610240 |
| 9 | 115391239875475200 |
| 10 | 115506631115350675200 |
| 11 | 153854832645647099366400 |
| 12 | 266015005644323834804505600 |
| 13 | 584700982406223788900303308800 |
| 14 | 1605004196705084300531332582656000 |
[1,2,18,504,32760,4127760,895723920,308129028480, 158070191610240,115391239875475200, 115506631115350675200,153854832645647099366400, 266015005644323834804505600, 584700982406223788900303308800, 1605004196705084300531332582656000] |