Simplify the expression

What is the pattern in the values as the exponents increase?

During a bike challenge riders have to collect various colored ribbons each 1/2 mile they collect a red ribbon each eighth mile they collect a green ribbon and each quarter mile they collect a blue ribbion wich colors of ribion will be collected at the 3/4 markrer

Pat listed all the numbers that have 15 as a multiple write the numbers in pats list