Write a computer program that takes as input positive integers a$,$ n and returns the value of a Fn$1($mod Fn$)$ Select some a $<$ F$4$ and check that F$4$ satisfies Fermat$$s little theorem. Can you find an a so that F$5$ does not satisfy FLT $($and therefore must be a composite number$)?$ Is F$6$ a composite number? How far can your machine handle Fermat numbers?