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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 25 |
| 7 | 70 |
| 8 | 226 |
| 9 | 753 |
| 10 | 2675 |
| 11 | 9785 |
| 12 | 37087 |
| 13 | 143487 |
| 14 | 566952 |
| 15 | 2274967 |
| 16 | 9257906 |
| 17 | 38113299 |
| 18 | 158535204 |
| 19 | 665364565 |
| 20 | 2814924441 |
| 21 | 11993967450 |
| 22 | 51433198599 |
| 23 | 221839745468 |
| 24 | 961884808879 |
| 25 | 4190783204515 |
| 26 | 18339291329225 |
[1,1,2,4,9,25,70,226,753,2675,9785,37087,143487, 566952,2274967,9257906,38113299,158535204, 665364565,2814924441,11993967450,51433198599, 221839745468,961884808879,4190783204515, 18339291329225] |