Triple Or Add Five

July 27, 2018

By starting from the number 1 and repeatedly either adding 5 or multiplying by 3, an infinite set of numbers can be generated. For instance, starting from 1, you can triple to get 3, then add five to get 8, and finally triple to get 24, so 24 is reachable. On the other hand, 15 is not reachable, as a little thought will show.

Your task is to write a program that determines if a number n is reachable by tripling or adding five, and if the number is reachable to give the sequence of operations by which it can be reached. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.

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