很好求的:Sn=a1+a2+a3+...+an=1*2^0+3*2^1+5*2^2+7*2^3+...+(2n-1)2^n-1 ①2Sn=1*2^1+3*2^2+5*2^3+7*2^4+...+(2n-3)*2^n-1+(2n-1)*2^n ②①-②得-Sn=1*2^0+2*2^1+2*2^2+2*2^3+...+2*2^n-1-(2n-1)*2^n =2^(n+1)+3-(2n...