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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 8 |
| 4 | 60 |
| 5 | 471 |
| 6 | 4911 |
| 7 | 78797 |
| 8 | 2207405 |
| 9 | 113740613 |
| 10 | 10926218807 |
| 11 | 1956363413115 |
| 12 | 652335084532025 |
| 13 | 405402273420833338 |
| 14 | 470568642161119515627 |
| 15 | 1023063423471189429817807 |
| 16 | 4178849203082023236054797465 |
| 17 | 32168008290073542372004072630072 |
| 18 | 468053896898117580623237189882068990 |
[0,0,1,8,60,471,4911,78797,2207405,113740613, 10926218807,1956363413115,652335084532025, 405402273420833338,470568642161119515627, 1023063423471189429817807, 4178849203082023236054797465, 32168008290073542372004072630072, 468053896898117580623237189882068990] |