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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 48 |
| 6 | 167 |
| 7 | 602 |
| 8 | 2256 |
| 9 | 8660 |
| 10 | 33958 |
| 11 | 135292 |
| 12 | 546422 |
| 13 | 2231462 |
| 14 | 9199869 |
| 15 | 38237213 |
| 16 | 160047496 |
| 17 | 674034147 |
| 18 | 2854137769 |
| 19 | 12144094756 |
| 20 | 51895919734 |
| 21 | 222634125803 |
| 22 | 958474338539 |
| 23 | 4139623680861 |
| 24 | 17931324678301 |
| 25 | 77880642231286 |
| 26 | 339093495674090 |
| 27 | 1479789701661116 |
[1,1,2,5,15,48,167,602,2256,8660,33958,135292, 546422,2231462,9199869,38237213,160047496, 674034147,2854137769,12144094756,51895919734, 222634125803,958474338539,4139623680861, 17931324678301,77880642231286,339093495674090, 1479789701661116] |