I've red some information about Femat. There was 2 interesting theorems, for which I can't find proof in the internet. So if anyone has some ideas how to proof that and can share them - thanks in advance.
1) 26 is the only number between perfect square and cube (25 and 27).
2) Every prime, that has reminder 1 when divised by 4 is sum of two squares. I tried to prove that, but i stucked up.