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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 15 |
| 5 | 192 |
| 6 | 2530 |
| 7 | 36165 |
| 8 | 570507 |
| 9 | 9969400 |
| 10 | 192525084 |
| 11 | 4087525095 |
| 12 | 94813475185 |
| 13 | 2387594185944 |
| 14 | 64886220442290 |
| 15 | 1892895183489583 |
| 16 | 58997625514583385 |
| 17 | 1956486468000839280 |
| 18 | 68781080882461076488 |
| 19 | 2555098360335768584385 |
| 20 | 100009432504671913008351 |
[1,0,0,1,15,192,2530,36165,570507,9969400, 192525084,4087525095,94813475185,2387594185944, 64886220442290,1892895183489583,58997625514583385, 1956486468000839280,68781080882461076488, 2555098360335768584385,100009432504671913008351] |