(- 8 2 4 1 )(- 20 July 8, 2019 16 32 64 128 1 2 4 8 16 upto 20 terms 2 8 20 x 1 1 4 0 5 1 2 4 8 16 upto 20 terms sum 2 8 ( 20 x1 1 4 0 5 8รท2(2+2)=1 or 16 2 -4 8 -16
