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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 6 |
| 3 | 25 |
| 4 | 90 |
| 5 | 295 |
| 6 | 945 |
| 7 | 2995 |
| 8 | 9450 |
| 9 | 29749 |
| 10 | 93555 |
| 11 | 294058 |
| 12 | 924041 |
| 13 | 2903320 |
| 14 | 9121612 |
| 15 | 28657269 |
| 16 | 90030844 |
| 17 | 282842403 |
| 18 | 888579011 |
| 19 | 2791558622 |
| 20 | 8769948429 |
| 21 | 27551618702 |
| 22 | 86555983552 |
| 23 | 271923674474 |
| 24 | 854273468992 |
| 25 | 2683779334331 |
| 26 | 8431341566236 |
| 27 | 26487840921750 |
| 28 | 83214006759229 |
| 29 | 261424512797515 |
[0,6,25,90,295,945,2995,9450,29749,93555,294058, 924041,2903320,9121612,28657269,90030844, 282842403,888579011,2791558622,8769948429, 27551618702,86555983552,271923674474,854273468992, 2683779334331,8431341566236,26487840921750, 83214006759229,261424512797515] |