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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 97 |
| 6 | 418 |
| 7 | 1800 |
| 8 | 7717 |
| 9 | 32969 |
| 10 | 140558 |
| 11 | 598590 |
| 12 | 2547851 |
| 13 | 10842145 |
| 14 | 46133086 |
| 15 | 196287336 |
| 16 | 835152025 |
| 17 | 3553338593 |
| 18 | 15118441034 |
| 19 | 64324630854 |
| 20 | 273682864751 |
| 21 | 1164442223761 |
| 22 | 4954368527338 |
| 23 | 21079421416440 |
| 24 | 89686912218205 |
| 25 | 381592176237641 |
| 26 | 1623565645450934 |
| 27 | 6907807794533022 |
[1,1,2,6,23,97,418,1800,7717,32969,140558,598590, 2547851,10842145,46133086,196287336,835152025, 3553338593,15118441034,64324630854,273682864751, 1164442223761,4954368527338,21079421416440, 89686912218205,381592176237641,1623565645450934, 6907807794533022] |