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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 36 |
| 5 | 196 |
| 6 | 1248 |
| 7 | 9128 |
| 8 | 75520 |
| 9 | 697936 |
| 10 | 7130400 |
| 11 | 79830272 |
| 12 | 972224064 |
| 13 | 12798573376 |
| 14 | 181124475392 |
| 15 | 2742464277632 |
| 16 | 44241677392896 |
| 17 | 757593444234496 |
| 18 | 13725165351006720 |
| 19 | 262293328557596672 |
| 20 | 5273316901853946880 |
[1,2,8,36,196,1248,9128,75520,697936,7130400, 79830272,972224064,12798573376,181124475392, 2742464277632,44241677392896,757593444234496, 13725165351006720,262293328557596672, 5273316901853946880] |