Unlikely you'll see this, so long after the fact, but oh well. My "method of substituting a variable" is nothing more than a more mathematically rigorous way o

Unlikely you'll see this, so long after the fact, but oh well. My "method of substituting a variable" is nothing more than a more mathematically rigorous way of observing that x^2 + 1 is not prime for any of the odd integers, which is roughly half of them. Of course, that's using a definition of "prime" that is at odds with yours, and I'll defer to your more advanced math knowledge in that regard.