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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 18 |
| 4 | 82 |
| 5 | 378 |
| 6 | 1760 |
| 7 | 8262 |
| 8 | 39044 |
| 9 | 185526 |
| 10 | 885596 |
| 11 | 4243590 |
| 12 | 20400954 |
| 13 | 98353278 |
| 14 | 475322352 |
| 15 | 2302064010 |
| 16 | 11170370850 |
| 17 | 54293503770 |
| 18 | 264290420540 |
| 19 | 1288257980310 |
| 20 | 6287181414470 |
| 21 | 30717958762350 |
| 22 | 150234512678480 |
| 23 | 735446569221810 |
| 24 | 3603330368706640 |
| 25 | 17668505697688098 |
| 26 | 86698739895529300 |
[1,4,18,82,378,1760,8262,39044,185526,885596, 4243590,20400954,98353278,475322352,2302064010, 11170370850,54293503770,264290420540, 1288257980310,6287181414470,30717958762350, 150234512678480,735446569221810,3603330368706640, 17668505697688098,86698739895529300] |