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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 24 |
| 4 | 252 |
| 5 | 3120 |
| 6 | 46650 |
| 7 | 823536 |
| 8 | 16777208 |
| 9 | 387420480 |
| 10 | 9999999990 |
| 11 | 285311670600 |
| 12 | 8916100448244 |
| 13 | 302875106592240 |
| 14 | 11112006825558002 |
| 15 | 437893890380859360 |
| 16 | 18446744073709551600 |
| 17 | 827240261886336764160 |
| 18 | 39346408075296537575406 |
| 19 | 1978419655660313589123960 |
[1,0,2,24,252,3120,46650,823536,16777208, 387420480,9999999990,285311670600,8916100448244, 302875106592240,11112006825558002, 437893890380859360,18446744073709551600, 827240261886336764160,39346408075296537575406, 1978419655660313589123960] |