DSolve[Derivative[1][y][x] == (1 + a + a^2*x + 3*a*x*y[x] + a^2*x*y[x] + 3*a^2*x^2*y[x]^2 + a^3*x^3*y[x]^3)/(a^2*x^2*(1 + a*x + a*x*y[x])),y[x],x]