Spiral of Primes
The natural numbers are arranged along an Archimedean spiral so that the squares 1, 4, 9, … are on the axis, with the primes drawn in blue, up to a circle of radius . The spiral is parametrized in polar coordinates by , . Also shown is the curve given by , (red), and its intersections with the spiral (purple boxes).
 R. Sacks. Number Spiral. (2007) www.numberspiral.com.
 H. Hahn. "The Distribution of Prime Numbers on the Square Root Spiral." arXiv. (Jan 9, 2008) arxiv.org/abs/0801.1441.