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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 89 |
| 5 | 579 |
| 6 | 3995 |
| 7 | 28721 |
| 8 | 212847 |
| 9 | 1614635 |
| 10 | 12477185 |
| 11 | 97877095 |
| 12 | 777397703 |
| 13 | 6239433601 |
| 14 | 50526305419 |
| 15 | 412314344295 |
| 16 | 3387257518809 |
| 17 | 27991418870939 |
| 18 | 232523406281683 |
| 19 | 1940567787973745 |
| 20 | 16263132449945319 |
| 21 | 136809398137470355 |
| 22 | 1154813296781074241 |
[0,1,3,15,89,579,3995,28721,212847,1614635, 12477185,97877095,777397703,6239433601, 50526305419,412314344295,3387257518809, 27991418870939,232523406281683,1940567787973745, 16263132449945319,136809398137470355, 1154813296781074241] |