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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 4 |
| 3 | 9 |
| 4 | 12 |
| 5 | 30 |
| 6 | 55 |
| 7 | 105 |
| 8 | 212 |
| 9 | 405 |
| 10 | 794 |
| 11 | 1551 |
| 12 | 3015 |
| 13 | 5889 |
| 14 | 11477 |
| 15 | 22374 |
| 16 | 43636 |
| 17 | 85068 |
| 18 | 165871 |
| 19 | 323418 |
| 20 | 630582 |
| 21 | 1229517 |
| 22 | 2397289 |
| 23 | 4674198 |
| 24 | 9113711 |
| 25 | 17769780 |
| 26 | 34647305 |
| 27 | 67554891 |
| 28 | 131717661 |
| 29 | 256821477 |
| 30 | 500747300 |
[0,4,9,12,30,55,105,212,405,794,1551,3015,5889, 11477,22374,43636,85068,165871,323418,630582, 1229517,2397289,4674198,9113711,17769780,34647305, 67554891,131717661,256821477,500747300] |