:?

What is the density of the following sets S_0 and S_1 in the natural numbers?

S = {n element of Natural numbers | n = 0 (mod 3) and n/2 not = 0 (mod 3)}

S_0 = {n element of S | 1/2(3n+1) is even}

S_1 = {n element of S | 1/2(3n+1) is odd}

What is the general way to compute it? Would it be strange if their densities are equal?