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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 49 |
| 6 | 168 |
| 7 | 595 |
| 8 | 2160 |
| 9 | 7997 |
| 10 | 30083 |
| 11 | 114660 |
| 12 | 441840 |
| 13 | 1718531 |
| 14 | 6737820 |
| 15 | 26600784 |
| 16 | 105659970 |
| 17 | 421949492 |
| 18 | 1693120779 |
| 19 | 6823018035 |
| 20 | 27602090087 |
| 21 | 112053680381 |
| 22 | 456343848121 |
| 23 | 1863893501065 |
| 24 | 7633232165286 |
| 25 | 31337360839387 |
| 26 | 128944120202510 |
[1,1,2,5,15,49,168,595,2160,7997,30083,114660, 441840,1718531,6737820,26600784,105659970, 421949492,1693120779,6823018035,27602090087, 112053680381,456343848121,1863893501065, 7633232165286,31337360839387,128944120202510] |