The Blancmange function is a fractal curve that is defined in this Wikipedia article. By definition, the curve stretches between x = 0 and x = 1 with an area underneath it of exactly 0.5.

Let C be the circle with center (0.25, 0.5) and radius r = 0.25.

What area under the Blancmange curve is enclosed by C?

(This problem came from Project Euler's site).