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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 56 |
| 3 | 392 |
| 4 | 2744 |
| 5 | 19208 |
| 6 | 134456 |
| 7 | 941192 |
| 8 | 6588316 |
| 9 | 46118016 |
| 10 | 322824768 |
| 11 | 2259763968 |
| 12 | 15818281920 |
| 13 | 110727512448 |
| 14 | 775089360192 |
| 15 | 5425602932736 |
| 16 | 37979062409652 |
| 17 | 265852330035768 |
| 18 | 1860958562459976 |
| 19 | 13026655702912824 |
[1,8,56,392,2744,19208,134456,941192,6588316, 46118016,322824768,2259763968,15818281920, 110727512448,775089360192,5425602932736, 37979062409652,265852330035768,1860958562459976, 13026655702912824] |