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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 47 |
| 4 | 654 |
| 5 | 12084 |
| 6 | 278682 |
| 7 | 7708056 |
| 8 | 248678784 |
| 9 | 9168447600 |
| 10 | 380274659760 |
| 11 | 17524760349216 |
| 12 | 888364833282000 |
| 13 | 49125202031205936 |
| 14 | 2942774373267939168 |
| 15 | 189829708902667840320 |
| 16 | 13118899353628035596544 |
| 17 | 966975804677206274688000 |
[1,1,5,47,654,12084,278682,7708056,248678784, 9168447600,380274659760,17524760349216, 888364833282000,49125202031205936, 2942774373267939168,189829708902667840320, 13118899353628035596544,966975804677206274688000] |