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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 6 |
| 6 | 13 |
| 7 | 34 |
| 8 | 91 |
| 9 | 257 |
| 10 | 754 |
| 11 | 2290 |
| 12 | 7185 |
| 13 | 23216 |
| 14 | 77019 |
| 15 | 261740 |
| 16 | 909353 |
| 17 | 3224262 |
| 18 | 11649471 |
| 19 | 42833407 |
| 20 | 160084445 |
| 21 | 607507992 |
| 22 | 2338760045 |
| 23 | 9126115359 |
| 24 | 36068187762 |
| 25 | 144279012291 |
| 26 | 583783534411 |
| 27 | 2387939881857 |
| 28 | 9869420688876 |
[0,1,1,3,6,13,34,91,257,754,2290,7185,23216,77019, 261740,909353,3224262,11649471,42833407,160084445, 607507992,2338760045,9126115359,36068187762, 144279012291,583783534411,2387939881857, 9869420688876] |