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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 72 |
| 4 | 6232 |
| 5 | 1621620 |
| 6 | 1241237520 |
| 7 | 2675188471920 |
| 8 | 15634073104902000 |
| 9 | 239929277724680059440 |
| 10 | 9411787539302194544158080 |
| 11 | 922671287397731617736789070720 |
| 12 | 221805878984619105095368813189002240 |
| 13 | 128660270226206951104782827202740054476800 |
[1,1,3,72,6232,1621620,1241237520,2675188471920, 15634073104902000,239929277724680059440, 9411787539302194544158080, 922671287397731617736789070720, 221805878984619105095368813189002240, 128660270226206951104782827202740054476800] |