![Ulam spirals: Visualizing properties of prime numbers with SAS](https://blogs.sas.com/content/iml/files/2013/10/ulamspiral.png)
Prime numbers are strange beasts. They exhibit properties of both randomness and regularity. Recently I watched an excellent nine-minute video on the Numberphile video blog that shows that if you write the natural numbers in a spiral pattern (called the Ulam spiral), then there are certain lines in the pattern