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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 7 |
| 4 | 74 |
| 5 | 882 |
| 6 | 11144 |
| 7 | 159652 |
| 8 | 2571960 |
| 9 | 46406392 |
| 10 | 928734944 |
| 11 | 20436096048 |
| 12 | 490489794464 |
| 13 | 12752891909920 |
| 14 | 357081983435904 |
| 15 | 10712466529388608 |
| 16 | 342798976818878336 |
| 17 | 11655165558112403328 |
| 18 | 419585962575107694080 |
[0,0,7,74,882,11144,159652,2571960,46406392, 928734944,20436096048,490489794464,12752891909920, 357081983435904,10712466529388608, 342798976818878336,11655165558112403328, 419585962575107694080] |