26465

As a diagram, the solution would be drawn in a square, then half of the gap is halved (to work it out, you need to double the denominator). The results are infinite, so when in numerical form they look like this: ½, ¼, 1/8, 1/16, 1/32, 1/64, 1/128. To work this out, all you do is to double the denominator to get half of the previous fraction.