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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 44 |
| 5 | 138 |
| 6 | 552 |
| 7 | 1863 |
| 8 | 7452 |
| 9 | 26230 |
| 10 | 104920 |
| 11 | 379038 |
| 12 | 1516152 |
| 13 | 5573492 |
| 14 | 22293968 |
| 15 | 82976111 |
| 16 | 331904444 |
| 17 | 1246784478 |
| 18 | 4987137912 |
| 19 | 18868203514 |
| 20 | 75472814056 |
| 21 | 287167092908 |
| 22 | 1148668371632 |
| 23 | 4390802287190 |
| 24 | 17563209148760 |
| 25 | 67393124281628 |
| 26 | 269572497126512 |
| 27 | 1037738919339676 |
| 28 | 4150955677358704 |
[1,1,4,11,44,138,552,1863,7452,26230,104920, 379038,1516152,5573492,22293968,82976111, 331904444,1246784478,4987137912,18868203514, 75472814056,287167092908,1148668371632, 4390802287190,17563209148760,67393124281628, 269572497126512,1037738919339676,4150955677358704] |