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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 5 |
| 5 | 11 |
| 6 | 44 |
| 7 | 134 |
| 8 | 529 |
| 9 | 1902 |
| 10 | 7793 |
| 11 | 31068 |
| 12 | 133641 |
| 13 | 574259 |
| 14 | 2594969 |
| 15 | 11842726 |
| 16 | 56083004 |
| 17 | 269450143 |
| 18 | 1333170844 |
| 19 | 6703500545 |
| 20 | 34548749471 |
| 21 | 181026885253 |
| 22 | 969167994094 |
| 23 | 5273977173249 |
| 24 | 29257773480987 |
| 25 | 164894374634333 |
| 26 | 945779302210358 |
| 27 | 5507572390808676 |
[1,0,1,1,5,11,44,134,529,1902,7793,31068,133641, 574259,2594969,11842726,56083004,269450143, 1333170844,6703500545,34548749471,181026885253, 969167994094,5273977173249,29257773480987, 164894374634333,945779302210358,5507572390808676] |