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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 6 |
| 3 | 6 |
| 4 | 21968100 |
| 5 | 100803789240 |
| 6 | 683751016938990 |
| 7 | 1651735848676253340 |
[4,6,6,21968100,100803789240,683751016938990, 1651735848676253340] |