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David Radcliffe
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David Radcliffe

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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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David Radcliffe

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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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I have a piece on Yitang Zhang's proof of bounded gaps and the notion of prime numbers as random numbers in Slate today: 
http://www.slate.com/articles/health_and_science/do_the_math/2013/05/yitang_zhang_twin_primes_conjecture_a_huge_discovery_about_prime_numbers.single.html
Last week, Yitang “Tom” Zhang, a popular math professor at the University of New Hampshire, stunned the world of pure mathematics when he announced that he had proven the “bounded gaps” conjecture about the distribution of prime numbers—a crucial milestone on the way to the even more elusive twin primes...
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David Radcliffe

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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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Definitely not.
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I wanted to share my Javascript application for searching for topological spaces. It's based on the tables from "Counterexamples in Topology" by Steen and Seebach.  I've been thinking about allowing users to add new topological spaces and properties to the database, but I'm not sure of the best way to manage this.
Topology Assistant. When you click on the name of a topological property, the cell background will change colors. If the background is light green, then the page will display topological spaces that have the given property. If the background is light pink, then the spaces that lack this property ...
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is this based purely on javascript?
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David Radcliffe

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Using Python to see how the Times writes about men and women. Neal Caren - University of North Carolina, Chapel Hill mail web twitter scholar. Do men and women come up in different contexts in the newspaper? One quick way to answer that question is to compare the words in sentences that discuss ...
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Have him in circles
462 people
Kristen Hinnegan's profile photo
Dongle lk's profile photo
putri bungsu's profile photo
Yuriy Shapovalov's profile photo
Ted Lakeland's profile photo
Daniel Shchur's profile photo
Bonita Deamicis's profile photo
Demetri Lales's profile photo
StudyGlobal Berlin'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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