我觉得,假设T=1+3x+5x^2+…+(2n-1)x^(n-1),那x×T=x+3x^2+5x^3+…+(2n-1)x^n.这样(1-x)×T=1+2x+2x^2+…+2x^(n-1)-(2n-1)x^n=1-(2n-1)x^n+2×(x+x^2+…+x^(n-1))=1-(2n-1)x^n+[2x×(1-x^n)]/1-x.再整理一下此式即可....