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David Radcliffe
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David Radcliffe

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I wrote a blog post discussing a question of Kurt Mahler: Which squares have only the digits 0 or 1 when written in base 5? I found all such squares less than 5^64 and proved that infinitely many are not divisible by 5.
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This is a directed graph with 1000 vertices, numbered from 0 to 999, and a directed edge from vertex n to vertex (n*n+2) mod 1000 for each n. I think it's rather pretty.
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Thanks for the invite; some good stuff here! Bill
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What can we say about the patterns of leading digits of (2^n, 3^n, ..., 9^n)? My answer is here.
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David Radcliffe

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Do the frequencies of Emoji characters follow Zipf's law?
Emojitracker.com is a very interesting site that tracks how often each emoji is used on Twitter. The statistics are updated in real time, and it's really quite amazing to watch. (In case the reader...
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I am investigating the sum of digits of 2^n. I have discovered an elementary proof that s(2^n) > log_4 n for all n. What is the best known lower bound for this sequence?
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Ah. In that case, I have discovered an elementary proof that s(2^n) is bounded.
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Definitely not.
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Have him in circles
468 people
rubén elías vega aguilar's profile photo
Esminee Rase's profile photo
Adam Fort's profile photo
Kristen Hinnegan's profile photo
Bryan Anderson's profile photo
sigit muhamad's profile photo
Richard Hung's profile photo
David Gray's profile photo
Amar Bapu's profile photo
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I am a college math instructor living in St. Paul MN. I am not a vice president at Google; that is a different David Radcliffe. I did not star in the Harry Potter movies; that is Daniel Radcliffe.
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