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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 70 |
| 5 | 263 |
| 6 | 1039 |
| 7 | 4201 |
| 8 | 17360 |
| 9 | 72965 |
| 10 | 310840 |
| 11 | 1338571 |
| 12 | 5820669 |
| 13 | 25504666 |
| 14 | 112537658 |
| 15 | 499493326 |
| 16 | 2228445752 |
| 17 | 9988153191 |
| 18 | 44949498534 |
| 19 | 203026168336 |
| 20 | 920042020632 |
| 21 | 4181646741701 |
| 22 | 19057370396166 |
| 23 | 87065535081027 |
| 24 | 398665735321696 |
| 25 | 1829253321634891 |
| 26 | 8409472030816278 |
| 27 | 38728745148056846 |
[1,2,6,19,70,263,1039,4201,17360,72965,310840, 1338571,5820669,25504666,112537658,499493326, 2228445752,9988153191,44949498534,203026168336, 920042020632,4181646741701,19057370396166, 87065535081027,398665735321696,1829253321634891, 8409472030816278,38728745148056846] |