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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 67 |
| 5 | 239 |
| 6 | 1031 |
| 7 | 2501 |
| 8 | 36579 |
| 9 | 109915 |
| 10 | 468653 |
| 11 | 1043851 |
| 12 | 9395751 |
| 13 | 21232827 |
| 14 | 97493519 |
| 15 | 235880373 |
| 16 | 7717800611 |
| 17 | 17385733651 |
| 18 | 82456426833 |
| 19 | 175398844079 |
| 20 | 1578297716013 |
| 21 | 3634938193489 |
| 22 | 15867173716609 |
| 23 | 34517119775523 |
| 24 | 619312307079687 |
| 25 | 1363237700933583 |
[1,1,3,13,67,239,1031,2501,36579,109915,468653, 1043851,9395751,21232827,97493519,235880373, 7717800611,17385733651,82456426833,175398844079, 1578297716013,3634938193489,15867173716609, 34517119775523,619312307079687,1363237700933583] |