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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 9 |
| 4 | 360 |
| 5 | 9000 |
| 6 | 7000 |
| 7 | 343000 |
| 8 | 8232000 |
| 9 | 666792000 |
| 10 | 7334712000 |
| 11 | 887500152000 |
| 12 | 11537501976000 |
| 13 | 1949837833944000 |
| 14 | 1949837833944000 |
| 15 | 1949837833944000 |
| 16 | 265177945416384000 |
| 17 | 76636426225334976000 |
| 18 | 161788010920151616000 |
[1,9,360,9000,7000,343000,8232000,666792000, 7334712000,887500152000,11537501976000, 1949837833944000,1949837833944000, 1949837833944000,265177945416384000, 76636426225334976000,161788010920151616000] |