visualizingmath:The Ulam SpiralThe prime spiral, also known as Ulam’s spiral, is a plot in which the
visualizingmath:The Ulam SpiralThe prime spiral, also known as Ulam’s spiral, is a plot in which the positive integers are arranged in a spiral with primes indicated in some way along the spiral. Unexpected patterns of diagonal lines are apparent in such a plot. This construction was first made by Polish-American mathematician Stanislaw Ulam (1909-1986) in 1963 while doodling during a boring talk at a scientific meeting. While drawing a grid of lines, he decided to number the intersections according to a spiral pattern, and then began circling the numbers in the spiral that were primes. Surprisingly, the circled primes appeared to fall along a number of diagonal straight lines or, in Ulam’s slightly more formal prose, it “appears to exhibit a strongly nonrandom appearance”In the above variation of the Ulam spiral, red squares represent prime numbers and white squares represent non-primes. Image source. -- source link