How do you solve this question ?if (1+x+x^2)^6 = a0 + a1 x + a2 x^2 + ..........+ a12 x^12, then the value of 2a0 + a1 + 2a2+ a3 + 2a4 + ............. + a11 + 2a12 is

1) (3^6 + 1) / 2
2) 3(3^6 + 1) / 2
3) (3^7 + 1) / 2
4) 3(3^5 + 1) / 2