Am 02.01.2016 um 14:14 schrieb yehudak .: > Thank you so much, but... > All that is Chinese for me. > Can you show a 'normal' Python code for me? How about: >>> from math import log >>> sum([int(0.2**k*n) for k in range(1, int(log(n, 5))+1)]) }:-) (That implements my procedure in my other answer.) -- Robin Koch