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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 21 |
| 3 | 42 |
| 4 | 125 |
| 5 | 361 |
| 6 | 987 |
| 7 | 2840 |
| 8 | 8177 |
| 9 | 23078 |
| 10 | 66092 |
| 11 | 189934 |
| 12 | 542549 |
| 13 | 1555968 |
| 14 | 4472084 |
| 15 | 12834117 |
| 16 | 36874076 |
| 17 | 106057815 |
| 18 | 304978090 |
| 19 | 877344581 |
| 20 | 2525161569 |
| 21 | 7268401508 |
| 22 | 20925202372 |
| 23 | 60256501068 |
| 24 | 173532468268 |
| 25 | 499807464421 |
| 26 | 1439715507607 |
[4,21,42,125,361,987,2840,8177,23078,66092,189934, 542549,1555968,4472084,12834117,36874076, 106057815,304978090,877344581,2525161569, 7268401508,20925202372,60256501068,173532468268, 499807464421,1439715507607] |