我把组合数记作C(n,0)等等．ω＝cos(2π/3)+isin(2π/3),ω＾2＝cos(4π/3)+isin(4π/3),ω^3＝cos(6π/3)+isin(6π/3)=1.1+ω+ω^2=0.(1+x)^n=C(n,0)+C(n,1)x+C(n,2)x^2+C(n,3)x^3+.令x=1,得C(n,0)+C(n,1)+C(n,2)+C...