✓ Mathematica : cpu = 7.62071 (sec), leaf count = 109
DSolve[Derivative[1][y][x] == (x*y[x]^3)/(3*E^((3*x^2)/2)*(3*E^((3*x^2)/2) + 3*y[x] + E^((3*x^2)/2)*y[x])),y[x],x]
✓ Maple : cpu = 1.664 (sec), leaf count = 143
dsolve(diff(y(x),x) = 1/3*y(x)^3*x*exp(3*x^2)/(3*exp(3/2*x^2)+exp(3/2*x^2)*y(x)+3*y(x))/exp(9/2*x^2),y(x))