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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 25 |
| 5 | 66 |
| 6 | 283 |
| 7 | 840 |
| 8 | 3756 |
| 9 | 12069 |
| 10 | 54948 |
| 11 | 186098 |
| 12 | 858580 |
| 13 | 3022402 |
| 14 | 14080499 |
| 15 | 51067222 |
| 16 | 239576208 |
| 17 | 889609995 |
| 18 | 4197132776 |
| 19 | 15888680266 |
| 20 | 75300462988 |
| 21 | 289674695513 |
| 22 | 1377953936275 |
| 23 | 5373571333590 |
| 24 | 25642014979659 |
| 25 | 101174320326663 |
| 26 | 484087207491429 |
| 27 | 1929609515826074 |
| 28 | 9254070911112520 |
[1,1,3,6,25,66,283,840,3756,12069,54948,186098, 858580,3022402,14080499,51067222,239576208, 889609995,4197132776,15888680266,75300462988, 289674695513,1377953936275,5373571333590, 25642014979659,101174320326663,484087207491429, 1929609515826074,9254070911112520] |