Yeah no idea, where they got that from. Fermat argued in the 1630s that this was impossible, Euler then proved it in the 18th century. [Actually, Fermat claime

Yeah no idea, where they got that from. Fermat argued in the 1630s that this was impossible, Euler then proved it in the 18th century. [Actually, Fermat claimed that a^n+b^n=c^n is impossible for n>2, but the proof for that wasn't discovered until the 1990s. It's Andrew Wiles's famous proof of Fermat's Last Theorem.]