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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 18 |
| 4 | 360 |
| 5 | 14460 |
| 6 | 994680 |
| 7 | 109021500 |
| 8 | 17815754880 |
| 9 | 4147063256448 |
| 10 | 1323985303267200 |
| 11 | 562636176102554400 |
| 12 | 310405397451855552000 |
| 13 | 217731000904433587359360 |
| 14 | 190749857434239995742090240 |
| 15 | 205540893695782384696324368000 |
| 16 | 268793206446238988670401236992000 |
[1,1,2,18,360,14460,994680,109021500,17815754880, 4147063256448,1323985303267200,562636176102554400, 310405397451855552000,217731000904433587359360, 190749857434239995742090240, 205540893695782384696324368000, 268793206446238988670401236992000] |