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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 21 |
| 3 | 102 |
| 4 | 503 |
| 5 | 2504 |
| 6 | 12505 |
| 7 | 62506 |
| 8 | 312507 |
| 9 | 1562508 |
| 10 | 7812509 |
| 11 | 39062510 |
| 12 | 195312511 |
| 13 | 976562512 |
| 14 | 4882812513 |
| 15 | 24414062514 |
| 16 | 122070312515 |
| 17 | 610351562516 |
| 18 | 3051757812517 |
| 19 | 15258789062518 |
| 20 | 76293945312519 |
| 21 | 381469726562520 |
| 22 | 1907348632812521 |
| 23 | 9536743164062522 |
| 24 | 47683715820312523 |
| 25 | 238418579101562524 |
[4,21,102,503,2504,12505,62506,312507,1562508, 7812509,39062510,195312511,976562512,4882812513, 24414062514,122070312515,610351562516, 3051757812517,15258789062518,76293945312519, 381469726562520,1907348632812521,9536743164062522, 47683715820312523,238418579101562524] |