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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 35 |
| 6 | 125 |
| 7 | 425 |
| 8 | 1628 |
| 9 | 6034 |
| 10 | 24212 |
| 11 | 94981 |
| 12 | 393857 |
| 13 | 1606466 |
| 14 | 6821063 |
| 15 | 28606253 |
| 16 | 123619645 |
| 17 | 529230526 |
| 18 | 2318216292 |
| 19 | 10082257498 |
| 20 | 44639650166 |
| 21 | 196562094912 |
| 22 | 877864578830 |
| 23 | 3904062637293 |
| 24 | 17560866279815 |
| 25 | 78732428712281 |
| 26 | 356268432627579 |
| 27 | 1608057486202905 |
| 28 | 7313491585387718 |
[1,1,2,4,12,35,125,425,1628,6034,24212,94981, 393857,1606466,6821063,28606253,123619645, 529230526,2318216292,10082257498,44639650166, 196562094912,877864578830,3904062637293, 17560866279815,78732428712281,356268432627579, 1608057486202905,7313491585387718] |