In 1225, Emperor Frederick II challenged the mathematician Fibonacci to take part in a mathematical contest against several other mathematicians, with three problems set by his court philosopher John of Palermo. The first of these problems asked for three rational numbers whose squares were equally spaced five units apart, solved by Fibonacci with the three numbers 31 12 {\displaystyle {\tfrac {31}{12}}} , 41 12 {\displaystyle {\tfrac {41}{12}}} , and 49 12 {\displaystyle {\tfrac {49}{12}}} . In The Book of Squares, published later the same year by Fibonacci, he solved the more general problem of finding triples of square numbers that are equally spaced from each other, forming an arithmetic progression.