Find sequence 1 / 2, 3 / 4, 5 / 8, 16 / 17 The sum of the first n terms of 2N-1 / 2 ^ n A problem in the summation of sequence

Find sequence 1 / 2, 3 / 4, 5 / 8, 16 / 17 The sum of the first n terms of 2N-1 / 2 ^ n A problem in the summation of sequence

Sn = 1×1/2 + 3×1/4 + 5×1/8 + ... + (2n-3)/2^(n-1) + (2n-1)/2^nSn/2 = 1×1/4 + 3×1/8 + 5×1/16 + ...+ (2n-3)/2^n + 2n-1/2^(n+1)Sn - Sn/2 = 1/2 - 1 + 2( 1/2 + 1/4 + 1/8 + ...+ 1/2^n ) - 2n-1/2^(n+1)...