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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 3 |
| 2 | 1 |
| 3 | 23 |
| 4 | 97 |
| 5 | 423 |
| 6 | 2961 |
| 7 | 4343 |
| 8 | 63169 |
| 9 | 245575 |
| 10 | 408305 |
| 11 | 1809559 |
| 12 | 84001 |
| 13 | 50919655 |
| 14 | 155110993 |
| 15 | 548906039 |
| 16 | 2768600449 |
| 17 | 15085235847 |
| 18 | 36877174193 |
| 19 | 258140219351 |
| 20 | 707469907681 |
| 21 | 2753266098215 |
| 22 | 10476769665297 |
| 23 | 20560829523831 |
| 24 | 73557062489153 |
| 25 | 233424460713415 |
[0,3,1,23,97,423,2961,4343,63169,245575,408305, 1809559,84001,50919655,155110993,548906039, 2768600449,15085235847,36877174193,258140219351, 707469907681,2753266098215,10476769665297, 20560829523831,73557062489153,233424460713415] |