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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 31 |
| 5 | 99 |
| 6 | 411 |
| 7 | 1512 |
| 8 | 6497 |
| 9 | 25717 |
| 10 | 113560 |
| 11 | 470615 |
| 12 | 2119435 |
| 13 | 9069212 |
| 14 | 41430503 |
| 15 | 181543837 |
| 16 | 838373030 |
| 17 | 3740867568 |
| 18 | 17423551011 |
| 19 | 78857867841 |
| 20 | 369838661718 |
| 21 | 1693046404678 |
| 22 | 7985762164083 |
| 23 | 36898943558246 |
| 24 | 174881314068075 |
| 25 | 814316512661987 |
| 26 | 3875201367249076 |
| 27 | 18161941728609720 |
| 28 | 86733820305600697 |
[1,1,3,8,31,99,411,1512,6497,25717,113560,470615, 2119435,9069212,41430503,181543837,838373030, 3740867568,17423551011,78857867841,369838661718, 1693046404678,7985762164083,36898943558246, 174881314068075,814316512661987,3875201367249076, 18161941728609720,86733820305600697] |