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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 18 |
| 3 | 11250 |
| 4 | 64854011250 |
| 5 | 2980024297506569894680811250 |
| 6 | 1319492964487055911863581348741902326769016593763234907139211250 |
[2,18,11250,64854011250, 2980024297506569894680811250, 13194929644870559118635813487419023267690165937632\ 34907139211250] |