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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 49 |
| 5 | 203 |
| 6 | 833 |
| 7 | 3533 |
| 8 | 15133 |
| 9 | 65891 |
| 10 | 289865 |
| 11 | 1288491 |
| 12 | 5774847 |
| 13 | 26076165 |
| 14 | 118501583 |
| 15 | 541605705 |
| 16 | 2487893725 |
| 17 | 11480052755 |
| 18 | 53188676889 |
| 19 | 247337349095 |
| 20 | 1154007818323 |
| 21 | 5400694067345 |
| 22 | 25345508567027 |
| 23 | 119251934995963 |
| 24 | 562414480094339 |
| 25 | 2658260322324013 |
[0,1,3,13,49,203,833,3533,15133,65891,289865, 1288491,5774847,26076165,118501583,541605705, 2487893725,11480052755,53188676889,247337349095, 1154007818323,5400694067345,25345508567027, 119251934995963,562414480094339,2658260322324013] |