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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 400 |
| 3 | 1054200 |
| 4 | 12243840000 |
| 5 | 429355384500000 |
| 6 | 39489843246336000000 |
| 7 | 7875251932432856328000000 |
| 8 | 3103313606339070135803904000000 |
| 9 | 2222194400107579127937216888000000000 |
[1,400,1054200,12243840000,429355384500000, 39489843246336000000,7875251932432856328000000, 3103313606339070135803904000000, 2222194400107579127937216888000000000] |