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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 21 |
| 3 | 249 |
| 4 | 4302 |
| 5 | 98982 |
| 6 | 2860686 |
| 7 | 99779418 |
| 8 | 4081683744 |
| 9 | 191696903424 |
| 10 | 10168315038360 |
| 11 | 601321398385320 |
| 12 | 39230551252853424 |
| 13 | 2799199551778309872 |
| 14 | 216856533870111053520 |
| 15 | 18127987493141612555280 |
| 16 | 1626479163148212406506240 |
| 17 | 155902932291162161594016000 |
[1,3,21,249,4302,98982,2860686,99779418, 4081683744,191696903424,10168315038360, 601321398385320,39230551252853424, 2799199551778309872,216856533870111053520, 18127987493141612555280,1626479163148212406506240, 155902932291162161594016000] |