simplify 1 + (x/6)((1 + x + x^2 + 2*x^3 + b*x^4)^3 + 3(1 + x + x^2 + 2*x^3 + b*x^4)(1 + x^2 + x^4 + 2*x^6 + b*x^8) + 2(1 + x^3 + x^6 + 2*x^9+ b*x^12) )