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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 2 |
| 7 | 1 |
| 8 | 4 |
| 9 | 88 |
| 10 | 0 |
| 11 | 976 |
| 12 | 22277 |
| 13 | 22365 |
| 14 | 376002 |
| 15 | 3172018 |
| 16 | 5821944 |
| 17 | 10222624 |
| 18 | 424452210 |
| 19 | 6129894510 |
| 20 | 38164752224 |
[0,0,0,0,0,2,1,4,88,0,976,22277,22365,376002, 3172018,5821944,10222624,424452210,6129894510, 38164752224] |