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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 20 |
| 3 | 100 |
| 4 | 500 |
| 5 | 2500 |
| 6 | 12500 |
| 7 | 62500 |
| 8 | 312500 |
| 9 | 1562500 |
| 10 | 7812500 |
| 11 | 39062500 |
| 12 | 195312500 |
| 13 | 976562500 |
| 14 | 4882812500 |
| 15 | 24414062500 |
| 16 | 122070312500 |
| 17 | 610351562500 |
| 18 | 3051757812500 |
| 19 | 15258789062500 |
| 20 | 76293945312500 |
| 21 | 381469726562500 |
| 22 | 1907348632812500 |
| 23 | 9536743164062500 |
[1,4,20,100,500,2500,12500,62500,312500,1562500, 7812500,39062500,195312500,976562500,4882812500, 24414062500,122070312500,610351562500, 3051757812500,15258789062500,76293945312500, 381469726562500,1907348632812500,9536743164062500] |