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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 51 |
| 6 | 191 |
| 7 | 780 |
| 8 | 3440 |
| 9 | 16249 |
| 10 | 81736 |
| 11 | 435796 |
| 12 | 2453100 |
| 13 | 14529728 |
| 14 | 90294625 |
| 15 | 587256087 |
| 16 | 3988153356 |
| 17 | 28223370977 |
| 18 | 207745253237 |
| 19 | 1587804229045 |
| 20 | 12581186077773 |
| 21 | 103197641796678 |
| 22 | 875085283793768 |
| 23 | 7661468372063681 |
| 24 | 69173450911547978 |
| 25 | 643354845906697516 |
[1,1,2,5,15,51,191,780,3440,16249,81736,435796, 2453100,14529728,90294625,587256087,3988153356, 28223370977,207745253237,1587804229045, 12581186077773,103197641796678,875085283793768, 7661468372063681,69173450911547978, 643354845906697516] |