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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 8 |
| 3 | 104 |
| 4 | 1040 |
| 5 | 9680 |
| 6 | 88088 |
| 7 | 795704 |
| 8 | 7170080 |
| 9 | 64556960 |
| 10 | 581091368 |
| 11 | 5230058504 |
| 12 | 47071235120 |
| 13 | 423643241840 |
| 14 | 3812795553848 |
| 15 | 34315179116504 |
| 16 | 308836669444160 |
| 17 | 2779530197184320 |
| 18 | 25015772291219528 |
| 19 | 225141952170657704 |
| 20 | 2026277574184965200 |
| 21 | 18236498181611824400 |
[0,8,104,1040,9680,88088,795704,7170080,64556960, 581091368,5230058504,47071235120,423643241840, 3812795553848,34315179116504,308836669444160, 2779530197184320,25015772291219528, 225141952170657704,2026277574184965200, 18236498181611824400] |