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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 40320 |
| 9 | 362880 |
| 10 | 3628800 |
| 11 | 32659200 |
| 12 | 267805440 |
| 13 | 2033498880 |
| 14 | 14563332000 |
| 15 | 100185340320 |
| 16 | 672903217200 |
| 17 | 4472291398032 |
| 18 | 29721557854116 |
| 19 | 199059839989844 |
[1,1,2,6,24,120,720,5040,40320,362880,3628800, 32659200,267805440,2033498880,14563332000, 100185340320,672903217200,4472291398032, 29721557854116,199059839989844] |