Plugging any number into N isn't how you would solve this. Take for example:
n = n^2-2
Plug in 5, you get: 5 = 23. Now, plug in 2, you get: 2 = 2.
BECAUSE KNOWLEDGE IS POWER!
But, this doesn't work.
Because, on the left side of the equation we have a number. On the right side, we have the same number times itself plus 1.
If the +1 wasn't there, 0 would work, but it is, so it doesn't.
I don't know, weird imaginary numbers might work, and I don't feel like working with negatives at this hour, but I'm pretty sure they don't work because -x^whatever, you basically disregard the -.