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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 28 |
| 3 | 108 |
| 4 | 400 |
| 5 | 1486 |
| 6 | 5516 |
| 7 | 20464 |
| 8 | 75912 |
| 9 | 281590 |
| 10 | 1044532 |
| 11 | 3874588 |
| 12 | 14372392 |
| 13 | 53312926 |
| 14 | 197758868 |
| 15 | 733566368 |
| 16 | 2721089680 |
| 17 | 10093604838 |
| 18 | 37441198412 |
| 19 | 138884309516 |
| 20 | 515177191104 |
| 21 | 1910997283694 |
| 22 | 7088649655580 |
| 23 | 26294623424272 |
| 24 | 97537225651992 |
| 25 | 361804397590486 |
| 26 | 1342076537863268 |
[6,28,108,400,1486,5516,20464,75912,281590, 1044532,3874588,14372392,53312926,197758868, 733566368,2721089680,10093604838,37441198412, 138884309516,515177191104,1910997283694, 7088649655580,26294623424272,97537225651992, 361804397590486,1342076537863268] |