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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 22 |
| 5 | 90 |
| 6 | 404 |
| 7 | 1974 |
| 8 | 10366 |
| 9 | 57864 |
| 10 | 341690 |
| 11 | 2134022 |
| 12 | 14104624 |
| 13 | 98498972 |
| 14 | 723664482 |
| 15 | 5561589508 |
| 16 | 44473028634 |
| 17 | 368602225688 |
| 18 | 3159852790392 |
| 19 | 27997141025686 |
| 20 | 256410638073082 |
| 21 | 2428063270357748 |
| 22 | 23774001479212114 |
| 23 | 240580239864321604 |
| 24 | 2513553050765310236 |
[1,2,6,22,90,404,1974,10366,57864,341690,2134022, 14104624,98498972,723664482,5561589508, 44473028634,368602225688,3159852790392, 27997141025686,256410638073082,2428063270357748, 23774001479212114,240580239864321604, 2513553050765310236] |