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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 18 |
| 5 | 92 |
| 6 | 588 |
| 7 | 4328 |
| 8 | 35920 |
| 9 | 338437 |
| 10 | 3654751 |
| 11 | 45105744 |
| 12 | 625582147 |
| 13 | 9539374171 |
| 14 | 157031052142 |
| 15 | 2757275781918 |
| 16 | 51293875591794 |
| 17 | 1007329489077804 |
| 18 | 20840741773898303 |
| 19 | 453654220906310222 |
| 20 | 10380640686263467204 |
| 21 | 249559854371799622350 |
| 22 | 6301679967177242849680 |
[1,2,5,18,92,588,4328,35920,338437,3654751, 45105744,625582147,9539374171,157031052142, 2757275781918,51293875591794,1007329489077804, 20840741773898303,453654220906310222, 10380640686263467204,249559854371799622350, 6301679967177242849680] |