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| n | a(n) |
|---|---|
| 2 | 8 |
| 3 | 60 |
| 4 | 400 |
| 5 | 2500 |
| 6 | 15000 |
| 7 | 87500 |
| 8 | 500000 |
| 9 | 2812500 |
| 10 | 15625000 |
| 11 | 85937500 |
| 12 | 468750000 |
| 13 | 2539062500 |
| 14 | 13671875000 |
| 15 | 73242187500 |
| 16 | 390625000000 |
| 17 | 2075195312500 |
| 18 | 10986328125000 |
| 19 | 57983398437500 |
| 20 | 305175781250000 |
| 21 | 1602172851562500 |
[8,60,400,2500,15000,87500,500000,2812500, 15625000,85937500,468750000,2539062500, 13671875000,73242187500,390625000000, 2075195312500,10986328125000,57983398437500, 305175781250000,1602172851562500] |