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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 10 |
| 4 | 206 |
| 5 | 6520 |
| 6 | 279736 |
| 7 | 15181296 |
| 8 | 997487440 |
| 9 | 76992086336 |
| 10 | 6829150642240 |
| 11 | 684529750280576 |
| 12 | 76524539192084096 |
| 13 | 9440085602432363520 |
| 14 | 1273845857661955460096 |
| 15 | 186655067329617703720960 |
| 16 | 29514780183694348261738496 |
| 17 | 5009445771827759781276491776 |
| 18 | 908381310192753648470120243200 |
[1,1,10,206,6520,279736,15181296,997487440, 76992086336,6829150642240,684529750280576, 76524539192084096,9440085602432363520, 1273845857661955460096,186655067329617703720960, 29514780183694348261738496, 5009445771827759781276491776, 908381310192753648470120243200] |