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Only figured it out for symmetric triplets...
Assume for some and . The sum and product of the triplet are:
- Sum:
- Product:
We set the sum equal to the product:
Assuming , divide both sides by :
This leads to the equation:
Thus, . For to be a natural number, must be a perfect square.
- For :
The triplet is (x - d, x, x + d) = (1, 2, 3).
No other values of yield a perfect square for , because is not a perfect square for .
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Haven't worked it out fully, but I think it would go something like this:
Suppose a+b+c=abc.
Then for any x,y,z>0:
(a+x)(b+y)(c+z)>(a+x)+(b+y)+(c+z)
We'd only have to check x,y,z>0 because you asked for natural number solutions, and we know 1,2,3 is the smallest such solution.