Do my best (图)

My major is not prob.,but I can say something.First,we get 13m+i(i= 0,1,2,...12) the prob.is the same(big n). Why:4-times the number the numbers increse expect vanue is to 13m+i+14=13(m+1)+i+1.So...,n times later,we get 3m+0 is 1/13