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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 8 |
| 4 | 39 |
| 5 | 190 |
| 6 | 861 |
| 7 | 3943 |
| 8 | 17867 |
| 9 | 81496 |
| 10 | 372378 |
| 11 | 1709842 |
| 12 | 7879360 |
| 13 | 36454004 |
| 14 | 169239651 |
| 15 | 788311290 |
| 16 | 3683018475 |
| 17 | 17255646688 |
| 18 | 81056033636 |
| 19 | 381668479192 |
| 20 | 1801188588566 |
| 21 | 8517994717214 |
| 22 | 40360814900566 |
| 23 | 191589547228523 |
| 24 | 911009396044132 |
| 25 | 4338777661726040 |
[0,0,1,8,39,190,861,3943,17867,81496,372378, 1709842,7879360,36454004,169239651,788311290, 3683018475,17255646688,81056033636,381668479192, 1801188588566,8517994717214,40360814900566, 191589547228523,911009396044132,4338777661726040] |