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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 18 |
| 3 | 82 |
| 4 | 374 |
| 5 | 1706 |
| 6 | 7782 |
| 7 | 35498 |
| 8 | 161926 |
| 9 | 738634 |
| 10 | 3369318 |
| 11 | 15369322 |
| 12 | 70107974 |
| 13 | 319801226 |
| 14 | 1458790182 |
| 15 | 6654348458 |
| 16 | 30354161926 |
| 17 | 138462112714 |
| 18 | 631602239718 |
| 19 | 2881086973162 |
| 20 | 13142230386374 |
| 21 | 59948977985546 |
| 22 | 273460429154982 |
| 23 | 1247404189803818 |
| 24 | 5690100090709126 |
[1,4,18,82,374,1706,7782,35498,161926,738634, 3369318,15369322,70107974,319801226,1458790182, 6654348458,30354161926,138462112714,631602239718, 2881086973162,13142230386374,59948977985546, 273460429154982,1247404189803818,5690100090709126] |