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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 6 |
| 2 | 20 |
| 3 | 265 |
| 4 | 1980 |
| 5 | 11584 |
| 6 | 11584 |
| 7 | 246882 |
| 8 | 1070425 |
| 9 | 29894430 |
| 10 | 29894430 |
| 11 | 1159795426 |
| 12 | 9069102398 |
| 13 | 9069102398 |
| 14 | 202847123212 |
| 15 | 2237516341759 |
| 16 | 2237516341759 |
| 17 | 201635099759365 |
| 18 | 1132157155708193 |
| 19 | 6017397949439540 |
| 20 | 17416293134812683 |
| 21 | 496169890920484689 |
| 22 | 1613261619087052703 |
[0,6,20,265,1980,11584,11584,246882,1070425, 29894430,29894430,1159795426,9069102398, 9069102398,202847123212,2237516341759, 2237516341759,201635099759365,1132157155708193, 6017397949439540,17416293134812683, 496169890920484689,1613261619087052703] |