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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 9 |
| 5 | 30 |
| 6 | 68 |
| 7 | 195 |
| 8 | 483 |
| 9 | 1309 |
| 10 | 3355 |
| 11 | 8900 |
| 12 | 23112 |
| 13 | 60813 |
| 14 | 158717 |
| 15 | 416325 |
| 16 | 1088661 |
| 17 | 2852242 |
| 18 | 7463884 |
| 19 | 19546175 |
| 20 | 51163695 |
| 21 | 133962621 |
| 22 | 350695511 |
| 23 | 918170280 |
| 24 | 2403740304 |
| 25 | 6293172025 |
| 26 | 16475579353 |
| 27 | 43133883845 |
| 28 | 112925557953 |
[0,1,1,5,9,30,68,195,483,1309,3355,8900,23112, 60813,158717,416325,1088661,2852242,7463884, 19546175,51163695,133962621,350695511,918170280, 2403740304,6293172025,16475579353,43133883845, 112925557953] |