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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | -12 |
| 4 | 216 |
| 5 | -5616 |
| 6 | 186624 |
| 7 | -7387200 |
| 8 | 335736576 |
| 9 | -17124804864 |
| 10 | 965515500288 |
| 11 | -59526188983296 |
| 12 | 3980690988235776 |
| 13 | -286917239797788672 |
| 14 | 22174720816561975296 |
| 15 | -1829668999418480590848 |
| 16 | 160570117472696852299776 |
| 17 | -14937971163165634577301504 |
| 18 | 1468791751381133837013319680 |
| 19 | -152229793395391092702181785600 |
| 20 | 16589818156062623434747885780992 |
| 21 | -1896733533500219982388526312325120 |
[1,2,-12,216,-5616,186624,-7387200,335736576, -17124804864,965515500288,-59526188983296, 3980690988235776,-286917239797788672, 22174720816561975296,-1829668999418480590848, 160570117472696852299776, -14937971163165634577301504, 1468791751381133837013319680, -152229793395391092702181785600, 16589818156062623434747885780992, -1896733533500219982388526312325120] |