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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 6 |
| 3 | 30 |
| 4 | 666 |
| 5 | 6524 |
| 6 | 103378 |
| 7 | 1250904 |
| 8 | 17976376 |
| 9 | 235892592 |
| 10 | 3296371800 |
| 11 | 44713314784 |
| 12 | 621198984864 |
| 13 | 8554092568512 |
| 14 | 118954438125472 |
| 15 | 1651089670102400 |
| 16 | 23021868920182656 |
| 17 | 321109217833684736 |
| 18 | 4490028930013194112 |
[0,6,30,666,6524,103378,1250904,17976376, 235892592,3296371800,44713314784,621198984864, 8554092568512,118954438125472,1651089670102400, 23021868920182656,321109217833684736, 4490028930013194112] |