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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 20 |
| 6 | 60 |
| 7 | 196 |
| 8 | 589 |
| 9 | 1907 |
| 10 | 6516 |
| 11 | 21860 |
| 12 | 75589 |
| 13 | 267566 |
| 14 | 950279 |
| 15 | 3423629 |
| 16 | 12499661 |
| 17 | 45919855 |
| 18 | 170274916 |
| 19 | 636617648 |
| 20 | 2394733039 |
| 21 | 9067049073 |
| 22 | 34535991913 |
| 23 | 132213431523 |
| 24 | 508684283599 |
| 25 | 1966124324293 |
| 26 | 7630970742790 |
| 27 | 29734868078582 |
| 28 | 116292627615997 |
| 29 | 456375717434690 |
| 30 | 1796789652244346 |
[1,1,1,3,9,20,60,196,589,1907,6516,21860,75589, 267566,950279,3423629,12499661,45919855,170274916, 636617648,2394733039,9067049073,34535991913, 132213431523,508684283599,1966124324293, 7630970742790,29734868078582,116292627615997, 456375717434690,1796789652244346] |