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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 10 |
| 3 | 23 |
| 4 | 51 |
| 5 | 110 |
| 6 | 233 |
| 7 | 488 |
| 8 | 1013 |
| 9 | 2088 |
| 10 | 4278 |
| 11 | 8720 |
| 12 | 17695 |
| 13 | 35768 |
| 14 | 72054 |
| 15 | 144717 |
| 16 | 289887 |
| 17 | 579312 |
| 18 | 1155257 |
| 19 | 2299426 |
| 20 | 4568935 |
| 21 | 9064316 |
| 22 | 17957296 |
| 23 | 35529320 |
| 24 | 70213565 |
| 25 | 138607340 |
| 26 | 273351142 |
| 27 | 538591471 |
| 28 | 1060310343 |
| 29 | 2085784818 |
| 30 | 4100099321 |
[4,10,23,51,110,233,488,1013,2088,4278,8720,17695, 35768,72054,144717,289887,579312,1155257,2299426, 4568935,9064316,17957296,35529320,70213565, 138607340,273351142,538591471,1060310343, 2085784818,4100099321] |