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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 8 |
| 5 | 24 |
| 6 | 106 |
| 7 | 546 |
| 8 | 3368 |
| 9 | 24032 |
| 10 | 195170 |
| 11 | 1777650 |
| 12 | 17950552 |
| 13 | 199059672 |
| 14 | 2405063018 |
| 15 | 31448531954 |
| 16 | 442501797656 |
| 17 | 6666753146496 |
| 18 | 107081325959938 |
| 19 | 1826636018849442 |
[1,2,2,8,24,106,546,3368,24032,195170,1777650, 17950552,199059672,2405063018,31448531954, 442501797656,6666753146496,107081325959938, 1826636018849442] |