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First, we replace with being tangents on the inscribed circle, as in
The inequality thus becomes
which is
or
First, for the upper bound
which is obviously true because is
Second, for the lower bound
Is equivalent to
The sum must be >= 0 because each summand is.
The shortest path is
If you look at that path in iterations 1-3, you see that it cuts through solid squares in two symmetric ways, in such a way that the next iteration's hole just barely misses it. Due to the fractal nature, this repeats with all subsequent iterations, infinitely.
I think the answer is in Why do perfect squares have a odd amount of factors
The squares are exactly those numbers with an odd amount of factors. Because the amount is odd, they are now open.