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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 4 |
| 8 | 44 |
| 9 | 280 |
| 10 | 1304 |
| 11 | 12452 |
| 12 | 105012 |
| 13 | 977664 |
| 14 | 9239816 |
| 15 | 90776620 |
| 16 | 897446092 |
[0,0,0,0,0,0,4,44,280,1304,12452,105012,977664, 9239816,90776620,897446092] |