王守恩 发表于 2023-3-11 18:57
简单一点:
0,5,27,78,170,315,525,812,1188,1665,2255,2970,3822,.... - f[n_] := Table[
- Solve[{s1 == x*y/2, s2 == z (2 n - x)/2,
- s3 == (2 n - y) (2 n - z)/2,
- s4 == (2 n) (2 n)/2 - s1 - s2 - s3}, {s1, s2, s3, s4},
- Integers], {x, 1, 2 n - 1}, {y, x, 2 n - 1}, {z, 1, 2 n - 1}]
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注意到s2,s3取半时前半部分本就是整数,既然取整数解,可以忽略掉,如:
- f[n_] := Table[
- Solve[{s1 == x*y/2, s2 == x*z/2, s3 == y*z/2,
- s4 == (2 n) (2 n)/2 - s1 - s2 - s3}, {s1, s2, s3, s4},
- Integers], {x, 1, 2 n - 1}, {y, x, 2 n - 1}, {z, 1, 2 n - 1}]
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继续查看代码,s1,s2,s3为整数时,s4显然也是整数,可以去掉:
- f[n_] := Table[
- Solve[{s1 == x*y/2, s2 == x*z/2, s3 == y*z/2}, {s1, s2, s3},
- Integers], {x, 1, 2 n - 1}, {y, x, 2 n - 1}, {z, 1, 2 n - 1}]
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