Peter Kagey
@peterkagey.com
Maker, Educator, Mathematician | Assistant Professor at Cal Poly Pomona
“My interests include music, science, justice, animals, shapes, feelings” —Lisa Simpson
Creator of @oeistriangles.peterkagey.com.
“My interests include music, science, justice, animals, shapes, feelings” —Lisa Simpson
Creator of @oeistriangles.peterkagey.com.
In October 2014, a few months out of college, I made my first web app so users could submit examples of constructions of upper bounds for a graph theory problem.
This last week, I've updated it to make it more mobile-friendly and colorful! Try it out and see if you can improve any of the bounds!
This last week, I've updated it to make it more mobile-friendly and colorful! Try it out and see if you can improve any of the bounds!
Square Game
peterkagey.com
November 17, 2025 at 6:38 AM
In October 2014, a few months out of college, I made my first web app so users could submit examples of constructions of upper bounds for a graph theory problem.
This last week, I've updated it to make it more mobile-friendly and colorful! Try it out and see if you can improve any of the bounds!
This last week, I've updated it to make it more mobile-friendly and colorful! Try it out and see if you can improve any of the bounds!
Reposted by Peter Kagey
I am absolutely buzzing following the publication of my very first OEIS sequence.
oeis.org/A389751
Numbers k such that k^3 can be represented as the sum of k consecutive nonprimes.
Eg
a(3) = 9^3 = 76+77+78+80+81+82+84+85+86
Only the first 16 numbers found so far, so please come and add more!
oeis.org/A389751
Numbers k such that k^3 can be represented as the sum of k consecutive nonprimes.
Eg
a(3) = 9^3 = 76+77+78+80+81+82+84+85+86
Only the first 16 numbers found so far, so please come and add more!
A389751 - OEIS
oeis.org
November 12, 2025 at 1:42 PM
I am absolutely buzzing following the publication of my very first OEIS sequence.
oeis.org/A389751
Numbers k such that k^3 can be represented as the sum of k consecutive nonprimes.
Eg
a(3) = 9^3 = 76+77+78+80+81+82+84+85+86
Only the first 16 numbers found so far, so please come and add more!
oeis.org/A389751
Numbers k such that k^3 can be represented as the sum of k consecutive nonprimes.
Eg
a(3) = 9^3 = 76+77+78+80+81+82+84+85+86
Only the first 16 numbers found so far, so please come and add more!
Check out my new blog post on a prototype shelf that I designed and made out of cardboard based on the "squaring the square" problem, which asks if you can partition a square into smaller squares all of different sizes. (You can!)
Come for the photos, stay for the 3D model!
Come for the photos, stay for the 3D model!
Squaring the shelf
Designing a shelf based on the 'squaring the square' problem
peterkagey.com
November 13, 2025 at 1:20 AM
Check out my new blog post on a prototype shelf that I designed and made out of cardboard based on the "squaring the square" problem, which asks if you can partition a square into smaller squares all of different sizes. (You can!)
Come for the photos, stay for the 3D model!
Come for the photos, stay for the 3D model!
I got a shoutout in the 245th edition of Carnival of Mathematics!
Theorem of the Day
www.theoremoftheday.org
November 11, 2025 at 11:28 PM
I got a shoutout in the 245th edition of Carnival of Mathematics!
Reposted by Peter Kagey
Looks like #plotparty postcards have landed in mailboxes! Read my new blog post about the cards I designed.
November 5, 2025 at 10:21 PM
Looks like #plotparty postcards have landed in mailboxes! Read my new blog post about the cards I designed.
Reposted by Peter Kagey
HMC CS prof Lucas Bang is helping students gain access to learning & networking opportunities in the computer programming languages field. Bang received a three-year NSF grant to fund as many as 10 students per year to attend international workshops in programming languages. uqr.to/bang-nsf.
October 28, 2025 at 9:04 PM
HMC CS prof Lucas Bang is helping students gain access to learning & networking opportunities in the computer programming languages field. Bang received a three-year NSF grant to fund as many as 10 students per year to attend international workshops in programming languages. uqr.to/bang-nsf.
Triangle T(m,n) giving of number of steps in the Euclidean algorithm for gcd(m,n) with 0<=m<n.
OEIS sequence A051010 by Eric W. Weisstein.
(Even terms are drawn as dark hexagons and odd terms are drawn as light hexagons.)
(Even terms are drawn as dark hexagons and odd terms are drawn as light hexagons.)
October 28, 2025 at 2:47 AM
Triangle T(m,n) giving of number of steps in the Euclidean algorithm for gcd(m,n) with 0<=m<n.
Five years ago today, I asked a question on Stack Exchange about the number of "n-polytets," which are ways of gluing n tetrahedra together.
Recently user Deadcode (David Ellsworth) answered the question and used some novel ideas to extend OEIS sequence oeis.org/A276272 from a(6)–a(17)!
Recently user Deadcode (David Ellsworth) answered the question and used some novel ideas to extend OEIS sequence oeis.org/A276272 from a(6)–a(17)!
Gluing tetrahedra together
(This challenge exists to extend sequence A276272 in the On-Line Encyclopedia of Integer Sequences, and perhaps create a new OEIS sequence1.)
This is a code-challenge, which will have you write cod...
codegolf.stackexchange.com
October 27, 2025 at 8:14 PM
Five years ago today, I asked a question on Stack Exchange about the number of "n-polytets," which are ways of gluing n tetrahedra together.
Recently user Deadcode (David Ellsworth) answered the question and used some novel ideas to extend OEIS sequence oeis.org/A276272 from a(6)–a(17)!
Recently user Deadcode (David Ellsworth) answered the question and used some novel ideas to extend OEIS sequence oeis.org/A276272 from a(6)–a(17)!
I wrote a blog post about how I made an RSS feed that allows you to get updated when new sequences matching your search are added to the On-Line Encyclopedia of Integer Sequences (OEIS).
RSS for the OEIS
An RSS feed based on searches on the On-Line Encyclopedia of Integer Sequences
peterkagey.com
October 26, 2025 at 5:54 PM
I wrote a blog post about how I made an RSS feed that allows you to get updated when new sequences matching your search are added to the On-Line Encyclopedia of Integer Sequences (OEIS).
Reposted by Peter Kagey
Arbitrarily Close: An Introduction to Real Analysis has been published by 619 Wreath! Free PDF, Desmos, and GeoGebra available on my faculty webpage (at least for the time being): www.cpp.edu/faculty/jaro...
Hardcover and paperback copies are available from 619 Wreath: www.619wreath.com/acl.html
Hardcover and paperback copies are available from 619 Wreath: www.619wreath.com/acl.html
October 25, 2025 at 7:45 PM
Arbitrarily Close: An Introduction to Real Analysis has been published by 619 Wreath! Free PDF, Desmos, and GeoGebra available on my faculty webpage (at least for the time being): www.cpp.edu/faculty/jaro...
Hardcover and paperback copies are available from 619 Wreath: www.619wreath.com/acl.html
Hardcover and paperback copies are available from 619 Wreath: www.619wreath.com/acl.html
I made a RSS feed that to see when new sequences are posted to the On-Line Encyclopedia of Integer Sequences (OEIS).
For example, if you want to see all of my new sequences or all those with keyword "nice", subscribe to
api.peterkagey.com/oeis_feed.xm...
api.peterkagey.com/oeis_feed.xm...
For example, if you want to see all of my new sequences or all those with keyword "nice", subscribe to
api.peterkagey.com/oeis_feed.xm...
api.peterkagey.com/oeis_feed.xm...
October 25, 2025 at 6:50 PM
I made a RSS feed that to see when new sequences are posted to the On-Line Encyclopedia of Integer Sequences (OEIS).
For example, if you want to see all of my new sequences or all those with keyword "nice", subscribe to
api.peterkagey.com/oeis_feed.xm...
api.peterkagey.com/oeis_feed.xm...
For example, if you want to see all of my new sequences or all those with keyword "nice", subscribe to
api.peterkagey.com/oeis_feed.xm...
api.peterkagey.com/oeis_feed.xm...
Reposted by Peter Kagey
I recently wrote a story about Peter Putnam, a forgotten physicist-turned-janitor with a groundbreaking theory of the mind, for @nautil.us. I was able to piece together Putnam's incredible story thanks to a few people who kept the ember of his work glowing for decades after his tragic death.
Finding Peter Putnam
The forgotten janitor who discovered the logic of the mind
nautil.us
July 23, 2025 at 8:19 PM
I recently wrote a story about Peter Putnam, a forgotten physicist-turned-janitor with a groundbreaking theory of the mind, for @nautil.us. I was able to piece together Putnam's incredible story thanks to a few people who kept the ember of his work glowing for decades after his tragic death.
Every Cobb salad is a macabre salad to me (because of the bacon).
October 24, 2025 at 2:05 AM
Every Cobb salad is a macabre salad to me (because of the bacon).
T(n,k) is the number number of partitions of n into distinct odd parts, where every part is ≤ k.
OEIS sequence A027359 by Clark Kimberling.
(Even terms are drawn as dark hexagons and odd terms are drawn as light hexagons.)
(Even terms are drawn as dark hexagons and odd terms are drawn as light hexagons.)
October 21, 2025 at 8:09 PM
T(n,k) is the number number of partitions of n into distinct odd parts, where every part is ≤ k.
Reposted by Peter Kagey
Tomorrow's the last day to get the "early bird" registration price for the Gathering 4 Gardner conference. This time, it will be in San Francisco! Featured speakers include computer scientist Donald Knuth, Mythbuster's Adam Savage, and Pixar's Danielle Feinberg. www.gathering4gardner.org/g4g16-info/
G4G16 Information
Early Registration Pricing Ends Oct 21st!G4G16 early registration is $595 with add-ons available for dinners and performances. Starting October 22nd, the registration price will increase to $695. T…
www.gathering4gardner.org
October 20, 2025 at 2:38 PM
Tomorrow's the last day to get the "early bird" registration price for the Gathering 4 Gardner conference. This time, it will be in San Francisco! Featured speakers include computer scientist Donald Knuth, Mythbuster's Adam Savage, and Pixar's Danielle Feinberg. www.gathering4gardner.org/g4g16-info/
Cool! Bert Dobbelaere and I counted that there are 10924738869 ways of putting 19 of these together! (oeis.org/A385024)
October 19, 2025 at 4:05 PM
Cool! Bert Dobbelaere and I counted that there are 10924738869 ways of putting 19 of these together! (oeis.org/A385024)
Reposted by Peter Kagey
Celebrated the centennial of the MAA SoCal-Nevada Section this afternoon by building the MAA icosahedron logo in real life! Designed by Glen Whitney, who oversaw the construction. @joinmaa.bsky.social
October 19, 2025 at 2:09 AM
Celebrated the centennial of the MAA SoCal-Nevada Section this afternoon by building the MAA icosahedron logo in real life! Designed by Glen Whitney, who oversaw the construction. @joinmaa.bsky.social
Reposted by Peter Kagey
If you work for ICE, you should quit.
October 4, 2025 at 11:09 PM
If you work for ICE, you should quit.
Triangle read by rows giving Whitney numbers [of the second kind] T(n,k) of Fibonacci lattices.
en.wikipedia.org/wiki/Matroid...
en.wikipedia.org/wiki/Matroid...
OEIS sequence A079487 by N. J. A. Sloane (January 2003).
(Even terms are drawn as dark hexagons and odd terms are drawn as light hexagons.)
(Even terms are drawn as dark hexagons and odd terms are drawn as light hexagons.)
October 11, 2025 at 4:54 PM
Triangle read by rows giving Whitney numbers [of the second kind] T(n,k) of Fibonacci lattices.
en.wikipedia.org/wiki/Matroid...
en.wikipedia.org/wiki/Matroid...
Reposted by Peter Kagey
There's a nice article by Siobhan Roberts about the Bridges 2025 conference in Eindhoven in the NY Times. I can now say that I am in The NY Times! (A photo credit for the shot of Chaim Goodman-Strauss and Edmund Harriss,... but still!) www.nytimes.com/2025/10/10/s...
Every Artist Has a Favorite Subject. For Some, That’s Math.
www.nytimes.com
October 10, 2025 at 7:20 PM
There's a nice article by Siobhan Roberts about the Bridges 2025 conference in Eindhoven in the NY Times. I can now say that I am in The NY Times! (A photo credit for the shot of Chaim Goodman-Strauss and Edmund Harriss,... but still!) www.nytimes.com/2025/10/10/s...
Reposted by Peter Kagey
Amazing: due to github.com/python/cpyth..., once you've updated to Python 3.14, you can use the command πthon to run your code
October 7, 2025 at 4:30 PM
Amazing: due to github.com/python/cpyth..., once you've updated to Python 3.14, you can use the command πthon to run your code
I was curious how many New Yorkers lived Upstate, so I looked on Wikipedia. The ratio of (population of NYC metro area)/(population of NY state) is (19940274)/(19867248)=1.00368, with a population of just -73026 people in Upstate New York.
October 7, 2025 at 4:56 PM
I was curious how many New Yorkers lived Upstate, so I looked on Wikipedia. The ratio of (population of NYC metro area)/(population of NY state) is (19940274)/(19867248)=1.00368, with a population of just -73026 people in Upstate New York.
Reposted by Peter Kagey
The #illustratingMath Seminar Online returns on Friday, October 10th, 9 am Pacific / 12 pm Eastern / 6 pm Europe. @3blue1brown.com will be "Exploring Zeta Function Visualizations." Gabriel and Jim will provide some "Show and Ask" input. See you online on Friday!
October 6, 2025 at 3:36 PM
The #illustratingMath Seminar Online returns on Friday, October 10th, 9 am Pacific / 12 pm Eastern / 6 pm Europe. @3blue1brown.com will be "Exploring Zeta Function Visualizations." Gabriel and Jim will provide some "Show and Ask" input. See you online on Friday!
I just re-designed my website away from Wordpress so that I could more easily embed 3D objects, Javascript, and more.
Check out my first blog post that takes advantage of these new features, based on a Bluesky post that I made back in May.
Check out my first blog post that takes advantage of these new features, based on a Bluesky post that I made back in May.
Pentagonal icositetrahedron puzzle
A puzzle on the faces of the pentagonal icositetrahedron with 3D models, STL files, photos, and video illustrations
peterkagey.com
October 6, 2025 at 1:46 AM
I just re-designed my website away from Wordpress so that I could more easily embed 3D objects, Javascript, and more.
Check out my first blog post that takes advantage of these new features, based on a Bluesky post that I made back in May.
Check out my first blog post that takes advantage of these new features, based on a Bluesky post that I made back in May.