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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 45 |
| 5 | 248 |
| 6 | 1032 |
| 7 | 3524 |
| 8 | 13173 |
| 9 | 54274 |
| 10 | 228712 |
| 11 | 917992 |
| 12 | 3608665 |
| 13 | 14286188 |
| 14 | 57438652 |
| 15 | 231343468 |
| 16 | 926921081 |
| 17 | 3700936774 |
| 18 | 14793198332 |
| 19 | 59241396140 |
| 20 | 237333611629 |
| 21 | 950127617692 |
| 22 | 3801974385964 |
| 23 | 15215432779936 |
| 24 | 60907523900693 |
| 25 | 243826775063490 |
| 26 | 976008753961184 |
[1,2,4,8,45,248,1032,3524,13173,54274,228712, 917992,3608665,14286188,57438652,231343468, 926921081,3700936774,14793198332,59241396140, 237333611629,950127617692,3801974385964, 15215432779936,60907523900693,243826775063490, 976008753961184] |