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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 3 |
| 2 | 13 |
| 3 | 40 |
| 4 | 108 |
| 5 | 275 |
| 6 | 681 |
| 7 | 1664 |
| 8 | 4040 |
| 9 | 9779 |
| 10 | 23637 |
| 11 | 57096 |
| 12 | 137876 |
| 13 | 332899 |
| 14 | 803729 |
| 15 | 1940416 |
| 16 | 4684624 |
| 17 | 11309731 |
| 18 | 27304157 |
| 19 | 65918120 |
| 20 | 159140476 |
| 21 | 384199155 |
| 22 | 927538873 |
| 23 | 2239276992 |
| 24 | 5406092952 |
| 25 | 13051462995 |
| 26 | 31509019045 |
| 27 | 76069501192 |
| 28 | 183648021540 |
| 29 | 443365544387 |
[0,3,13,40,108,275,681,1664,4040,9779,23637,57096, 137876,332899,803729,1940416,4684624,11309731, 27304157,65918120,159140476,384199155,927538873, 2239276992,5406092952,13051462995,31509019045, 76069501192,183648021540,443365544387] |