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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 20 |
| 5 | 76 |
| 6 | 313 |
| 7 | 1375 |
| 8 | 6337 |
| 9 | 30243 |
| 10 | 148129 |
| 11 | 739172 |
| 12 | 3737993 |
| 13 | 19077868 |
| 14 | 97955307 |
| 15 | 504707999 |
| 16 | 2604312205 |
| 17 | 13436676965 |
| 18 | 69229324721 |
| 19 | 355854322633 |
| 20 | 1823672937884 |
| 21 | 9314227843463 |
| 22 | 47406130512872 |
| 23 | 240498260267049 |
| 24 | 1216833204738419 |
| 25 | 6146116088495029 |
[1,1,2,6,20,76,313,1375,6337,30243,148129,739172, 3737993,19077868,97955307,504707999,2604312205, 13436676965,69229324721,355854322633, 1823672937884,9314227843463,47406130512872, 240498260267049,1216833204738419,6146116088495029] |