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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 25 |
| 4 | 100 |
| 5 | 409 |
| 6 | 1696 |
| 7 | 7230 |
| 8 | 31218 |
| 9 | 136348 |
| 10 | 601392 |
| 11 | 2668866 |
| 12 | 11926440 |
| 13 | 53590116 |
| 14 | 241861429 |
| 15 | 1096236518 |
| 16 | 4985474479 |
| 17 | 22743466843 |
| 18 | 104053210697 |
| 19 | 477225366201 |
| 20 | 2193758211686 |
| 21 | 10105182346741 |
| 22 | 46633811335305 |
| 23 | 215580754238987 |
| 24 | 998167033562149 |
| 25 | 4628378289705604 |
| 26 | 21490258193373055 |
| 27 | 99906737241167235 |
[1,2,7,25,100,409,1696,7230,31218,136348,601392, 2668866,11926440,53590116,241861429,1096236518, 4985474479,22743466843,104053210697,477225366201, 2193758211686,10105182346741,46633811335305, 215580754238987,998167033562149,4628378289705604, 21490258193373055,99906737241167235] |