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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 6 |
| 3 | 13 |
| 4 | 30 |
| 5 | 69 |
| 6 | 160 |
| 7 | 375 |
| 8 | 885 |
| 9 | 2102 |
| 10 | 5022 |
| 11 | 12060 |
| 12 | 29095 |
| 13 | 70485 |
| 14 | 171399 |
| 15 | 418220 |
| 16 | 1023663 |
| 17 | 2512761 |
| 18 | 6184253 |
| 19 | 15257262 |
| 20 | 37725972 |
| 21 | 93477778 |
| 22 | 232069116 |
| 23 | 577179078 |
| 24 | 1437926977 |
| 25 | 3587977293 |
| 26 | 8966170056 |
| 27 | 22437282917 |
| 28 | 56221762626 |
| 29 | 141051397725 |
[1,3,6,13,30,69,160,375,885,2102,5022,12060,29095, 70485,171399,418220,1023663,2512761,6184253, 15257262,37725972,93477778,232069116,577179078, 1437926977,3587977293,8966170056,22437282917, 56221762626,141051397725] |