Starting from the center of the picture, the spheres are
numbered (1, 2, 3,...) when following a
square spiral. The radius of the N-th sphere is proportional
to the square root of the number of divisors of N.
The number 1 and the prime numbers are visualized by means of white spheres
(a smaller one for the number 1).
(CMAP28 WWW site: this page was created on 02/08/1999 and last updated on 05/17/2026 18:04:49 -CEST-)
![The generalized Ulam spiral displaying 1000 numbers [La spirale d'Ulam généralisée montrant 1000 nombres entiers ]](image.jpg "The generalized Ulam spiral displaying 1000 numbers [La spirale d'Ulam généralisée montrant 1000 nombres entiers ]")