回複：答案

來源: 於 2010-05-02 11:26:07 [舊帖] [給我悄悄話] 本文已被閱讀：次

3+3^2+3^3+3^4+...3^n=(3^n-3)/(3-1)=.This result can be getting by induction using combining 3 to 1.The question is that 13 is not included in it.The answer may be not the Max.