For all positive integers n, let f3(n) be the representation of n in base 3, considered as a number in base 10. For example, since 5 in base 3 is 123, so f3(5)=12. What is the sum of all positive integers n such that f3(n)=8⋅n?

Answer 1

29

Answer 2

thanks very much but how it can be solved