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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 56 |
| 3 | 392 |
| 4 | 2736 |
| 5 | 19096 |
| 6 | 133288 |
| 7 | 930328 |
| 8 | 6493536 |
| 9 | 45323816 |
| 10 | 316352792 |
| 11 | 2208090536 |
| 12 | 15412109328 |
| 13 | 107573992120 |
| 14 | 750848799112 |
| 15 | 5240801312824 |
| 16 | 36579932515008 |
| 17 | 255321921769544 |
| 18 | 1782105084785144 |
| 19 | 12438800833105352 |
[1,8,56,392,2736,19096,133288,930328,6493536, 45323816,316352792,2208090536,15412109328, 107573992120,750848799112,5240801312824, 36579932515008,255321921769544,1782105084785144, 12438800833105352] |