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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 7 |
| 7 | 22 |
| 8 | 57 |
| 9 | 127 |
| 10 | 379 |
| 11 | 1849 |
| 12 | 9109 |
| 13 | 37324 |
| 14 | 128129 |
| 15 | 507508 |
| 16 | 3031393 |
| 17 | 19609773 |
| 18 | 108440893 |
| 19 | 500515633 |
| 20 | 2467616641 |
| 21 | 17154715726 |
| 22 | 134519207131 |
| 23 | 927764339426 |
| 24 | 5359830269641 |
| 25 | 31580724696907 |
| 26 | 248587878630807 |
| 27 | 2259650025239257 |
| 28 | 18541914182165557 |
[1,1,1,1,1,2,7,22,57,127,379,1849,9109,37324, 128129,507508,3031393,19609773,108440893, 500515633,2467616641,17154715726,134519207131, 927764339426,5359830269641,31580724696907, 248587878630807,2259650025239257, 18541914182165557] |