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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 16 |
| 4 | 120 |
| 5 | 456 |
| 6 | 2272 |
| 7 | 11044 |
| 8 | 49200 |
| 9 | 236196 |
| 10 | 1113296 |
| 11 | 5157772 |
| 12 | 24352896 |
| 13 | 114256032 |
| 14 | 534574312 |
| 15 | 2511482164 |
| 16 | 11778946872 |
| 17 | 55224573264 |
| 18 | 259130295272 |
| 19 | 1215413555584 |
| 20 | 5700599522328 |
| 21 | 26741489475588 |
| 22 | 125432405841016 |
[1,8,16,120,456,2272,11044,49200,236196,1113296, 5157772,24352896,114256032,534574312,2511482164, 11778946872,55224573264,259130295272, 1215413555584,5700599522328,26741489475588, 125432405841016] |