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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 25 |
| 3 | 3500 |
| 4 | 1348025 |
| 5 | 1752218300 |
| 6 | 5398931034000 |
| 7 | 22475921070676500 |
[1,25,3500,1348025,1752218300,5398931034000, 22475921070676500] |