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| n | a(n) |
|---|---|
| 3 | 0 |
| 4 | 0 |
| 5 | 2 |
| 6 | 6 |
| 7 | 4 |
| 8 | 20 |
| 9 | 34 |
| 10 | 96 |
| 11 | 234 |
| 12 | 626 |
| 13 | 1326 |
| 14 | 3616 |
| 15 | 9468 |
| 16 | 24157 |
| 17 | 59150 |
| 18 | 158218 |
| 19 | 412230 |
| 20 | 1070931 |
| 21 | 2789256 |
| 22 | 7413791 |
| 23 | 19502672 |
| 24 | 51743211 |
| 25 | 137439828 |
| 26 | 366790437 |
| 27 | 978701816 |
| 28 | 2624602885 |
| 29 | 7041724422 |
| 30 | 18946955025 |
[0,0,2,6,4,20,34,96,234,626,1326,3616,9468,24157, 59150,158218,412230,1070931,2789256,7413791, 19502672,51743211,137439828,366790437,978701816, 2624602885,7041724422,18946955025] |