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| n | a(n) |
|---|---|
| 1 | 180 |
| 2 | 1246 |
| 3 | 8870 |
| 4 | 65040 |
| 5 | 489772 |
| 6 | 3775022 |
| 7 | 29664576 |
| 8 | 236740252 |
| 9 | 1912108322 |
| 10 | 15584536740 |
| 11 | 127880485540 |
| 12 | 1054537633526 |
| 13 | 8727275684760 |
| 14 | 72413361371620 |
| 15 | 601955189383922 |
| 16 | 5010545177519292 |
| 17 | 41746084890460636 |
| 18 | 348047155647060662 |
[180,1246,8870,65040,489772,3775022,29664576, 236740252,1912108322,15584536740,127880485540, 1054537633526,8727275684760,72413361371620, 601955189383922,5010545177519292, 41746084890460636,348047155647060662] |