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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 14 |
| 5 | 47 |
| 6 | 154 |
| 7 | 514 |
| 8 | 1719 |
| 9 | 5901 |
| 10 | 20339 |
| 11 | 70137 |
| 12 | 245473 |
| 13 | 854033 |
| 14 | 3012779 |
| 15 | 10708332 |
[0,0,1,4,14,47,154,514,1719,5901,20339,70137, 245473,854033,3012779,10708332] |