✓ Mathematica : cpu = 130.245 (sec), leaf count = 27
DSolve[(1 + 6*x + 8*x^2 + 4*x^3 + x^4)*y[x] + (-2 - 12*x - 15*x^2 - 6*x^3 + x^6)*Derivative[1][y][x] - (-1 - 6*x - 6*x^2 + 3*x^4 + 2*x^6)*Derivative[2][y][x] + x^2*(1 + 2*x + 2*x^2 + x^4)*Derivative[3][y][x] == 0,y[x],x]
✓ Maple : cpu = 0.215 (sec), leaf count = 19
dsolve(x^2*(x^4+2*x^2+2*x+1)*diff(diff(diff(y(x),x),x),x)-(2*x^6+3*x^4-6*x^2-6*x-1)*diff(diff(y(x),x),x)+(x^6-6*x^3-15*x^2-12*x-2)*diff(y(x),x)+(x^4+4*x^3+8*x^2+6*x+1)*y(x)=0,y(x))