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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 12 |
| 4 | 72 |
| 5 | 2160 |
| 6 | 64800 |
| 7 | 13608000 |
| 8 | 2857680000 |
| 9 | 600112800000 |
| 10 | 126023688000000 |
| 11 | 291114719280000000 |
| 12 | 672475001536800000000 |
| 13 | 20194424296150104000000000 |
| 14 | 606438561613387623120000000000 |
| 15 | 18211350005250030322293600000000000 |
| 16 | 546886840657658410578476808000000000000 |
[1,1,2,12,72,2160,64800,13608000,2857680000, 600112800000,126023688000000,291114719280000000, 672475001536800000000,20194424296150104000000000, 606438561613387623120000000000, 18211350005250030322293600000000000, 546886840657658410578476808000000000000] |