Extraction factor 6 = 2×3. These powers of 2 and 3 are all smoke screens and have nothing to do with 13. As long as the formula = 13n is finally obtained. After extracting the n power of 3 and the n power of x6, there are 25x3=75 in front and 36 in the back. If you want to subtract 39x(3 to the n power, x6 to the n power), you can prove it.