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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 32 |
| 4 | 164 |
| 5 | 1032 |
| 6 | 7728 |
| 7 | 59376 |
| 8 | 522600 |
| 9 | 4946768 |
| 10 | 49680656 |
| 11 | 540031296 |
| 12 | 6195155744 |
| 13 | 75183755584 |
| 14 | 961596510272 |
| 15 | 12909563309952 |
| 16 | 181305865742240 |
| 17 | 2657525771641664 |
| 18 | 40594443765953472 |
| 19 | 643987597483557888 |
| 20 | 10601112599585001984 |
| 21 | 180727870834447607808 |
| 22 | 3185418524574895953152 |
[1,2,6,32,164,1032,7728,59376,522600,4946768, 49680656,540031296,6195155744,75183755584, 961596510272,12909563309952,181305865742240, 2657525771641664,40594443765953472, 643987597483557888,10601112599585001984, 180727870834447607808,3185418524574895953152] |