数列的通项为an=(2n-1)/2^(n-1)=2(n-1)/ 2^(n-1)+1/2^(n-1) (n为正整数)Sn=a1+a2+...+an=0+2/2+...+2(n-1)/2^(n-1)+[1+1/2+1/4+...1//2^(n-1)]=Bn+2*(1-1/2^n)=Bn+(2-1/2^(n-1))Bn=0+2/2+4/4+...+2(n-1)/2^(n-1)1/2*...