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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 2 |
| 4 | 16 |
| 5 | 192 |
| 6 | 3008 |
| 7 | 58480 |
| 8 | 1360896 |
| 9 | 36931328 |
| 10 | 1145967616 |
| 11 | 40040976384 |
| 12 | 1556236513280 |
| 13 | 66610814414848 |
| 14 | 3113899625938944 |
| 15 | 157874306413611008 |
| 16 | 8629070019375726592 |
| 17 | 505841319779582607360 |
| 18 | 31659277087340088786944 |
| 19 | 2107162955059322401718272 |
[1,0,2,16,192,3008,58480,1360896,36931328, 1145967616,40040976384,1556236513280, 66610814414848,3113899625938944, 157874306413611008,8629070019375726592, 505841319779582607360,31659277087340088786944, 2107162955059322401718272] |