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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 66 |
| 5 | 1071 |
| 6 | 27606 |
| 7 | 887305 |
| 8 | 34583357 |
| 9 | 1562797351 |
| 10 | 80177945542 |
| 11 | 4597212665432 |
| 12 | 291214532031215 |
| 13 | 20193430937073303 |
| 14 | 1521240318892230748 |
| 15 | 123711268485285686123 |
| 16 | 10801367759750192440520 |
| 17 | 1007762402877770768660697 |
| 18 | 100058924666668698411972015 |
| 19 | 10533938778032068908299390227 |
| 20 | 1172080056205294525370971027435 |
[1,0,1,5,66,1071,27606,887305,34583357,1562797351, 80177945542,4597212665432,291214532031215, 20193430937073303,1521240318892230748, 123711268485285686123,10801367759750192440520, 1007762402877770768660697, 100058924666668698411972015, 10533938778032068908299390227, 1172080056205294525370971027435] |