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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 24 |
| 5 | 71 |
| 6 | 224 |
| 7 | 710 |
| 8 | 2318 |
| 9 | 7659 |
| 10 | 25703 |
| 11 | 87153 |
| 12 | 298574 |
| 13 | 1031104 |
| 14 | 3587263 |
| 15 | 12558652 |
| 16 | 44214807 |
| 17 | 156438309 |
| 18 | 555973965 |
| 19 | 1983817178 |
| 20 | 7104313970 |
| 21 | 25525304569 |
| 22 | 91986529421 |
| 23 | 332408847422 |
| 24 | 1204259931815 |
| 25 | 4373027942634 |
| 26 | 15914143511582 |
| 27 | 58030451159889 |
[1,1,3,8,24,71,224,710,2318,7659,25703,87153, 298574,1031104,3587263,12558652,44214807, 156438309,555973965,1983817178,7104313970, 25525304569,91986529421,332408847422, 1204259931815,4373027942634,15914143511582, 58030451159889] |