ulam_spiral, a Python code which displays the integers as a spiral of grid cells, with the primes highlighted, so show that they tend to fall along diagonals, as discovered by Stanislaw Ulam.


The computer code and data files described and made available on this web page are distributed under the MIT license


ulam_spiral is available in a MATLAB version and an Octave version and a Python version.

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  1. Martin Gardner,
    Mathematical Games: The Remarkable Lore of the Prime Number,
    Scientific American,
    Volume 210, March 1964, pages 120-128.
  2. Martin Gardner,
    Sixth Book of Mathematical Diversion from Scientific American,
    ISBN13: 978-0-226-28250-3,
    University of Chicago Press, 1971.
  3. Christian Hill,
    The Ulam Spiral,
  4. Cleve Moler,
    Numerical Computing with MATLAB,
    SIAM, 2004,
    ISBN13: 978-0-898716-60-3,
    LC: QA297.M625,
    ebook: https://www.mathworks.com/moler/chapters.html

Source Code:

Last modified on 21 August 2023.