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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 5 |
| 3 | 14 |
| 4 | 27 |
| 5 | 66 |
| 6 | 180 |
| 7 | 484 |
| 8 | 1261 |
| 9 | 3346 |
| 10 | 8912 |
| 11 | 23666 |
| 12 | 62840 |
| 13 | 166959 |
| 14 | 443676 |
| 15 | 1178829 |
| 16 | 3132091 |
| 17 | 8322214 |
| 18 | 22112722 |
| 19 | 58754687 |
| 20 | 156114566 |
| 21 | 414806153 |
| 22 | 1102165608 |
| 23 | 2928521067 |
| 24 | 7781259792 |
| 25 | 20675285518 |
| 26 | 54935502703 |
| 27 | 145967000962 |
| 28 | 387843280136 |
[4,5,14,27,66,180,484,1261,3346,8912,23666,62840, 166959,443676,1178829,3132091,8322214,22112722, 58754687,156114566,414806153,1102165608, 2928521067,7781259792,20675285518,54935502703, 145967000962,387843280136] |