Richard1234 - It looks like your coefficients have gotten reversed - it is supposed to be 2x + a, not 2a + x. Hopefully that helps (or maybe that makes it worse for me!)
ebaines - You are correct about n=1. I never thought to go there. I will change my restriction on odd integers to be odd integers >= 3. This will prevent x+y = z since (x+y)^n > z^n for n>=3 if x^n + y^n = z^n. Allowing x+y=z seems to be what is letting you find the problems you found. Let me know.
Thank you both for your comments. I am quite new at this as you probably tell but enjoying it!