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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 19 |
| 3 | 94 |
| 4 | 470 |
| 5 | 2357 |
| 6 | 11829 |
| 7 | 59368 |
| 8 | 297902 |
| 9 | 1494469 |
| 10 | 7495425 |
| 11 | 37584962 |
| 12 | 188432209 |
| 13 | 944567955 |
| 14 | 4734350650 |
| 15 | 23727223169 |
| 16 | 118905239428 |
| 17 | 595839590228 |
| 18 | 2985639571718 |
| 19 | 14959922129662 |
| 20 | 74956381227810 |
| 21 | 375558759884508 |
| 22 | 1881652000369616 |
| 23 | 9427455976971208 |
| 24 | 47232924151619828 |
[1,4,19,94,470,2357,11829,59368,297902,1494469, 7495425,37584962,188432209,944567955,4734350650, 23727223169,118905239428,595839590228, 2985639571718,14959922129662,74956381227810, 375558759884508,1881652000369616,9427455976971208, 47232924151619828] |