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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 26 |
| 4 | 105 |
| 5 | 431 |
| 6 | 1827 |
| 7 | 7883 |
| 8 | 34355 |
| 9 | 151327 |
| 10 | 672562 |
| 11 | 3005578 |
| 12 | 13506779 |
| 13 | 60999340 |
| 14 | 276513218 |
| 15 | 1257747158 |
| 16 | 5739244040 |
| 17 | 26258189734 |
| 18 | 120423829974 |
| 19 | 553516970829 |
| 20 | 2549217000255 |
| 21 | 11761428696128 |
| 22 | 54355208008882 |
| 23 | 251586124907058 |
| 24 | 1166116972610051 |
| 25 | 5412142000435618 |
| 26 | 25149404570126040 |
| 27 | 116998424278050487 |
[1,2,7,26,105,431,1827,7883,34355,151327,672562, 3005578,13506779,60999340,276513218,1257747158, 5739244040,26258189734,120423829974,553516970829, 2549217000255,11761428696128,54355208008882, 251586124907058,1166116972610051,5412142000435618, 25149404570126040,116998424278050487] |