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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 10 |
| 3 | 22 |
| 4 | 97 |
| 5 | 213 |
| 6 | 381 |
| 7 | 1005 |
| 8 | 1900 |
| 9 | 4137 |
| 10 | 10518 |
| 11 | 21092 |
| 12 | 47994 |
| 13 | 111034 |
| 14 | 227786 |
| 15 | 526558 |
| 16 | 1173266 |
| 17 | 2506934 |
| 18 | 5760387 |
| 19 | 12607288 |
| 20 | 27523425 |
| 21 | 62352333 |
| 22 | 135931174 |
| 23 | 300820619 |
| 24 | 674058895 |
| 25 | 1474383381 |
| 26 | 3279987103 |
| 27 | 7290574867 |
| 28 | 16018404203 |
[4,10,22,97,213,381,1005,1900,4137,10518,21092, 47994,111034,227786,526558,1173266,2506934, 5760387,12607288,27523425,62352333,135931174, 300820619,674058895,1474383381,3279987103, 7290574867,16018404203] |