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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 6 |
| 6 | 27 |
| 7 | 122 |
| 8 | 555 |
| 9 | 2530 |
| 10 | 11564 |
| 11 | 52994 |
| 12 | 243467 |
| 13 | 1121292 |
| 14 | 5176432 |
| 15 | 23952042 |
| 16 | 111076279 |
| 17 | 516217844 |
| 18 | 2404051080 |
| 19 | 11218106730 |
| 20 | 52447788512 |
| 21 | 245659502752 |
| 22 | 1152673780946 |
| 23 | 5417690242696 |
| 24 | 25505048506311 |
| 25 | 120257626246616 |
| 26 | 567864679387562 |
[2,1,1,1,6,27,122,555,2530,11564,52994,243467, 1121292,5176432,23952042,111076279,516217844, 2404051080,11218106730,52447788512,245659502752, 1152673780946,5417690242696,25505048506311, 120257626246616,567864679387562] |