Although not related to pi, Fermat's last theorem is famous in the world of mathematics. With the formula an + bn = cn (a,b,c and n are whole numbers) , it can't be solved for positive number other than where n is 1 or 2 (Pythagoras). Proving this was the biggest challenge in mathematics since Fermat wrote in 1637 in a book that he had come up with a proof but the margin in the book wasn't big enough for his proof. It was eventually proved in 1994.
In 1864 a G W Pierce published a pamphlet where he claimed to have solved it It could be the strangest "proof" ever written. It ended with this. You've never seen anything like it 
