Ah one place I ran across this: see 16:05 of Knuth's 2017 Christmas lecture (https://www.youtube.com/watch?v=BxQw4CdxLr8 https://www.youtube.com/watch?v=BxQw4Cd

Ah one place I ran across this: see 16:05 of Knuth's 2017 Christmas lecture (https://www.youtube.com/watch?v=BxQw4CdxLr8 https://www.youtube.com/watch?v=BxQw4CdxLr8): > I got a nice piece of paper here to work with. They had a conference in Poland last year [BachoTeX 2016] and they sent me this nice pad of paper and I like it so much that I decided at my birthday party next month I gotta give out notepaper that's... [audio drowned by laughter] But actually the notepaper at my birthday party is going to be triangle... paper. Because I have a feeling that all kinds of mathematics has never been invented yet because people haven't been given triangle... [laughter].