Ulam spiral

Last updated at 7:49 pm UTC on 30 April 2018

https://tech.labs.oliverwyman.com/blog/2012/09/27/decomposing-the-ulam-spiral/The Ulam spiral is a well-known mystery to mathematicians: draw a 1 in a grid, 2 in the cell to the right, 3 above the 2, and so on in a spiral.

http://en.wikipedia.org/wiki/Ulam_spiral