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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 19 |
| 3 | 89 |
| 4 | 385 |
| 5 | 1601 |
| 6 | 6529 |
| 7 | 26369 |
| 8 | 105985 |
| 9 | 424961 |
| 10 | 1701889 |
| 11 | 6811649 |
| 12 | 27254785 |
| 13 | 109035521 |
| 14 | 436174849 |
| 15 | 1744764929 |
| 16 | 6979190785 |
| 17 | 27917025281 |
| 18 | 111668625409 |
| 19 | 446675550209 |
| 20 | 1786704297985 |
| 21 | 7146821386241 |
| 22 | 28587293933569 |
| 23 | 114349192511489 |
| 24 | 457396803600385 |
[1,4,19,89,385,1601,6529,26369,105985,424961, 1701889,6811649,27254785,109035521,436174849, 1744764929,6979190785,27917025281,111668625409, 446675550209,1786704297985,7146821386241, 28587293933569,114349192511489,457396803600385] |