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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 46 |
| 5 | 149 |
| 6 | 659 |
| 7 | 2359 |
| 8 | 10786 |
| 9 | 40881 |
| 10 | 190323 |
| 11 | 748193 |
| 12 | 3527018 |
| 13 | 14249557 |
| 14 | 67783120 |
| 15 | 279469503 |
| 16 | 1338252962 |
| 17 | 5605159863 |
| 18 | 26979650007 |
| 19 | 114453030191 |
| 20 | 553174729286 |
| 21 | 2371327312233 |
| 22 | 11499306561012 |
| 23 | 49727063025279 |
| 24 | 241807843147514 |
| 25 | 1053464596134725 |
| 26 | 5134560174599273 |
| 27 | 22512757056138723 |
[1,1,4,11,46,149,659,2359,10786,40881,190323, 748193,3527018,14249557,67783120,279469503, 1338252962,5605159863,26979650007,114453030191, 553174729286,2371327312233,11499306561012, 49727063025279,241807843147514,1053464596134725, 5134560174599273,22512757056138723] |