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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 8 |
| 3 | 22 |
| 4 | 232 |
| 5 | 1016 |
| 6 | 12496 |
| 7 | 73648 |
| 8 | 1032032 |
| 9 | 7586272 |
| 10 | 118141696 |
| 11 | 1033672256 |
| 12 | 17668427008 |
| 13 | 178649596672 |
| 14 | 3313667912192 |
| 15 | 37898019913216 |
| 16 | 756948065453056 |
| 17 | 9640771045925888 |
| 18 | 205935949714235392 |
| 19 | 2885307792776353792 |
| 20 | 65568056040976818176 |
[1,1,8,22,232,1016,12496,73648,1032032,7586272, 118141696,1033672256,17668427008,178649596672, 3313667912192,37898019913216,756948065453056, 9640771045925888,205935949714235392, 2885307792776353792,65568056040976818176] |