n | a(n) |
---|---|
0 | -1 |
1 | -1 |
2 | 1 |
3 | -2 |
4 | 6 |
5 | -24 |
6 | 120 |
7 | -720 |
8 | 5040 |
9 | -40320 |
10 | 362880 |
11 | -3628800 |
12 | 39916800 |
13 | -479001600 |
14 | 6227020800 |
15 | -87178291200 |
16 | 1307674368000 |
17 | -20922789888000 |
18 | 355687428096000 |
19 | -6402373705728000 |
20 | 121645100408832000 |
[-1,-1,1,-2,6,-24,120,-720,5040,-40320,362880, -3628800,39916800,-479001600,6227020800, -87178291200,1307674368000,-20922789888000, 355687428096000,-6402373705728000, 121645100408832000] |