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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 51 |
| 5 | 190 |
| 6 | 842 |
| 7 | 3431 |
| 8 | 15654 |
| 9 | 67330 |
| 10 | 312993 |
| 11 | 1392581 |
| 12 | 6555426 |
| 13 | 29833990 |
| 14 | 141757524 |
| 15 | 655762121 |
| 16 | 3137841689 |
| 17 | 14692467913 |
| 18 | 70689773071 |
| 19 | 334087875481 |
| 20 | 1614441359873 |
| 21 | 7686127259903 |
| 22 | 37274642271835 |
| 23 | 178505613655953 |
| 24 | 868232040289333 |
| 25 | 4177913803818686 |
| 26 | 20371131449476345 |
| 27 | 98416106111044095 |
[1,1,4,12,51,190,842,3431,15654,67330,312993, 1392581,6555426,29833990,141757524,655762121, 3137841689,14692467913,70689773071,334087875481, 1614441359873,7686127259903,37274642271835, 178505613655953,868232040289333,4177913803818686, 20371131449476345,98416106111044095] |