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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 15 |
| 6 | 24 |
| 7 | 213 |
| 8 | 356 |
| 9 | 2531 |
| 10 | 9710 |
| 11 | 46519 |
| 12 | 244683 |
| 13 | 891784 |
| 14 | 4720805 |
| 15 | 16462599 |
| 16 | 78516038 |
| 17 | 276022161 |
| 18 | 1161269082 |
| 19 | 4197268616 |
| 20 | 15926278724 |
| 21 | 58682897472 |
| 22 | 207708273846 |
| 23 | 766346150693 |
| 24 | 2617679503224 |
| 25 | 9515642240343 |
| 26 | 32088717865889 |
[1,1,1,2,15,24,213,356,2531,9710,46519,244683, 891784,4720805,16462599,78516038,276022161, 1161269082,4197268616,15926278724,58682897472, 207708273846,766346150693,2617679503224, 9515642240343,32088717865889] |