lim(m->∞) ∑(i:0->m) (0.5)^(n-i)=lim(m->∞) (0.5)^n ( 1- (0.5)^(m+1) )/( 1-0.5)=lim(m->∞) (0.5)^(n-1) ( 1- (0.5)^(m+1) )=(0.5)^(n-1)
