Category Archives: posts without words

Fermat witnesses and liars (some words on PWW #24)

Let be a positive integer we want to test for primality, and suppose is some other positive integer with . There are then four possibilities: and could share a common factor. In this case we can find the common factor … Continue reading

Posted in computation, number theory, posts without words, primes | Tagged , , , , | 1 Comment

Post without words #24

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Post without words #23

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Post without words #22

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Post without words #21

Posted in combinatorics, geometry, posts without words | Tagged , , | 17 Comments

From primitive roots to Euclid’s orchard

Commenter Snowball pointed out the similarity between Euclid’s Orchard… …and this picture of primitive roots I made a year ago: At first I didn’t see the connection, but Snowball was absolutely right. Once I understood it, I made this little … Continue reading

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A few words about PWW #20

A couple commenters quickly figured out what my previous post without words was about. The dots making up the image are at integer grid points , with the center at . There is a dot at if and only if … Continue reading

Posted in pattern, pictures, posts without words | Tagged , , | 10 Comments