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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 20 |
| 4 | 146 |
| 5 | 1660 |
| 6 | 24266 |
| 7 | 619885 |
| 8 | 24951532 |
| 9 | 1491389352 |
| 10 | 141842503743 |
| 11 | 21156539568960 |
| 12 | 4861988525864115 |
| 13 | 1744688422871068399 |
| 14 | 977626718408600885914 |
| 15 | 851525107752786868842753 |
[1,2,7,20,146,1660,24266,619885,24951532, 1491389352,141842503743,21156539568960, 4861988525864115,1744688422871068399, 977626718408600885914,851525107752786868842753] |