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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 50 |
| 4 | 130 |
| 5 | 296 |
| 6 | 610 |
| 7 | 1163 |
| 8 | 2097 |
| 9 | 3670 |
| 10 | 6434 |
| 11 | 11666 |
| 12 | 22313 |
| 13 | 44907 |
| 14 | 93206 |
| 15 | 194831 |
| 16 | 403141 |
| 17 | 818641 |
| 18 | 1628770 |
| 19 | 3184993 |
| 20 | 6157786 |
| 21 | 11854873 |
| 22 | 22877202 |
| 23 | 44459405 |
| 24 | 87168326 |
| 25 | 172249773 |
| 26 | 342083954 |
| 27 | 680463827 |
| 28 | 1351826291 |
| 29 | 2677343192 |
| 30 | 5283369867 |
[4,16,50,130,296,610,1163,2097,3670,6434,11666, 22313,44907,93206,194831,403141,818641,1628770, 3184993,6157786,11854873,22877202,44459405, 87168326,172249773,342083954,680463827,1351826291, 2677343192,5283369867] |