Sn=1/2+3/4+5/8+……+(2n-1)/2^n2Sn=1+3/2+5/4+……+(2n-1)/2^(n-1)两式错位相减Sn=1+[(3/2-1/2)+(5/4-3/4)+……+((2n-1)/2^(n-1)-(2n-3)/2^(n-1)]-(2n-1)/2^n=1+(2/2+2/4+2/8+……+2/2^(n-1))-(2n-1)/2^n=1+1×(1-1...