C[n,0] + C[n,3] + C[n,6] + ・・・ + C[n,3[n/3]] = {(1+ω)^n + (1-ω)^n}/2,

C[n,1] - C[n,2] + C[n,4] - C[n,5] + ・・・・ = (-i){(1+ω)^n - (1-ω)^n},