Profile

Cover photo
David Radcliffe
475 followers|99,671 views
AboutPosts

Stream

David Radcliffe

Shared publicly  - 
 
Interactive visual proof that every pentagonal number is 1/3 of a triangular number.
Triangular and pentagonal numbers. This applet illustrates the theorem that every pentagonal number is one-third of a triangular number. Drag the slider to change the size of the triangle. N = 8.
1
Add a comment...

David Radcliffe

Shared publicly  - 
 
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...
1
Add a comment...

David Radcliffe

Shared publicly  - 
 
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?
1
David Jao's profile photoDavid Radcliffe's profile photo
2 comments
 
Ah. In that case, I have discovered an elementary proof that s(2^n) is bounded.
Add a comment...

David Radcliffe

Shared publicly  - 
 
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.
2
David Radcliffe's profile photoRichard Green's profile photoWilliam Hutchison's profile photokorinエミ's profile photo
6 comments
 
great work thank you david
Add a comment...

David Radcliffe

Shared publicly  - 
2
Add a comment...
In his circles
143 people
Have him in circles
475 people
Ahmed Mohamed Abdulla's profile photo
Alan Cooper's profile photo
Bonita Deamicis's profile photo
Michael Kim's profile photo
David Spencer's profile photo
Peter Radcliffe's profile photo
Cindy Scofield's profile photo
Marie Durache's profile photo
Lloyd Cledwyn's profile photo

David Radcliffe

Shared publicly  - 
 
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.
1
Add a comment...

David Radcliffe

Shared publicly  - 
1
Add a comment...

David Radcliffe

Shared publicly  - 
 
Definitely not.
1
Add a comment...

David Radcliffe

Shared publicly  - 
1
Add a comment...
People
In his circles
143 people
Have him in circles
475 people
Ahmed Mohamed Abdulla's profile photo
Alan Cooper's profile photo
Bonita Deamicis's profile photo
Michael Kim's profile photo
David Spencer's profile photo
Peter Radcliffe's profile photo
Cindy Scofield's profile photo
Marie Durache's profile photo
Lloyd Cledwyn's profile photo
Basic Information
Gender
Male
Story
Introduction
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.
Links
Other profiles
Contributor to