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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 12 |
| 4 | 88 |
| 5 | 624 |
| 6 | 4112 |
| 7 | 32912 |
| 8 | 293280 |
| 9 | 2576896 |
| 10 | 23669376 |
| 11 | 233756544 |
| 12 | 2372829696 |
| 13 | 24679378432 |
| 14 | 268444154624 |
| 15 | 3026232635648 |
| 16 | 35050705650176 |
| 17 | 420323656792064 |
| 18 | 5218917552457728 |
| 19 | 66738035973859328 |
| 20 | 880566524142424064 |
| 21 | 11998061103578816512 |
| 22 | 168314109964357738496 |
[1,2,4,12,88,624,4112,32912,293280,2576896, 23669376,233756544,2372829696,24679378432, 268444154624,3026232635648,35050705650176, 420323656792064,5218917552457728, 66738035973859328,880566524142424064, 11998061103578816512,168314109964357738496] |