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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 2 |
| 6 | 19 |
| 7 | 150 |
| 8 | 1043 |
| 9 | 6843 |
| 10 | 43192 |
| 11 | 266529 |
| 12 | 1619983 |
| 13 | 9746883 |
| 14 | 58220994 |
| 15 | 345919915 |
[0,0,0,0,2,19,150,1043,6843,43192,266529,1619983, 9746883,58220994,345919915] |