[psyang]

Originally Posted by Mathgod

Spoiler!

f(5)=5 and my solution includes that, since 2^2+1=5
However, f(11)=13, so I will have to rethink this.

Spoiler!

I must have misunderstood. I thought you said the only solutions were 1 and values that were 3 mod 4. That's why I said 5 was a counter example since it is 1 mod 4.