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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 17 |
| 4 | 52 |
| 5 | 157 |
| 6 | 473 |
| 7 | 1420 |
| 8 | 4262 |
| 9 | 12788 |
| 10 | 38365 |
| 11 | 115097 |
| 12 | 345293 |
| 13 | 1035880 |
| 14 | 3107641 |
| 15 | 9322925 |
| 16 | 27968776 |
| 17 | 83906329 |
| 18 | 251718989 |
| 19 | 755156969 |
| 20 | 2265470908 |
| 21 | 6796412726 |
| 22 | 20389238179 |
| 23 | 61167714538 |
| 24 | 183503143616 |
| 25 | 550509430849 |
| 26 | 1651528292549 |
| 27 | 4954584877649 |
| 28 | 14863754632948 |
[0,1,5,17,52,157,473,1420,4262,12788,38365,115097, 345293,1035880,3107641,9322925,27968776,83906329, 251718989,755156969,2265470908,6796412726, 20389238179,61167714538,183503143616,550509430849, 1651528292549,4954584877649,14863754632948] |