Which of the following is not an example of an arithmetic sequence? 18 , 36 , 54 , 72 1 , 11 , 21 , 31 fraction numerator 6 over denominator 5 end fraction comma fraction numerator 16 over denominator 5 end fraction comma fraction numerator 24 over denominator 5 end fraction comma fraction numerator 34 over denominator 5 end fraction blank fraction numerator 2 over denominator 3 end fraction blank comma blank fraction numerator 5 over denominator 3 end fraction comma fraction numerator 8 over denominator 3 end fraction comma fraction numerator 11 over denominator 3 end fraction