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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 42 |
| 5 | 156 |
| 6 | 623 |
| 7 | 2562 |
| 8 | 10775 |
| 9 | 46314 |
| 10 | 202193 |
| 11 | 894617 |
| 12 | 4001675 |
| 13 | 18074562 |
| 14 | 82287790 |
| 15 | 377248774 |
| 16 | 1740375992 |
| 17 | 8071596078 |
| 18 | 37613773364 |
| 19 | 176041132719 |
| 20 | 827032930155 |
| 21 | 3898722302211 |
| 22 | 18437091951270 |
| 23 | 87434285061334 |
| 24 | 415710323685474 |
| 25 | 1981238899857338 |
| 26 | 9462805005034546 |
| 27 | 45286663139423310 |
[1,1,4,11,42,156,623,2562,10775,46314,202193, 894617,4001675,18074562,82287790,377248774, 1740375992,8071596078,37613773364,176041132719, 827032930155,3898722302211,18437091951270, 87434285061334,415710323685474,1981238899857338, 9462805005034546,45286663139423310] |