https://programmers.co.kr/learn/courses/30/lessons/12899
def solution(n):
answer = ''
base = ['1','2','4']
while n > 0:
n = n - 1
answer = base[n % 3] + answer
n = n // 3
return answer
n = n - 1
을 도출해낸 과정이 논리적이지 않았음