That of course means that 2021 is a semiprime (a product of two prime numbers).

The previous semiprime year was 2019 = 3 x 673.

Five years later it will be the next semiprime year, 2026 = 2 x 1013.

Almost all orbits of the Collatz map attain almost bounded values https://arxiv.org/abs/1909.03562

A Mathematical Coloring Book

Article by Hampton, Marshall

In collections: Art, Easily explained, Things to make and do

URL: http://www.d.umn.edu/~mhampton/mathcolor17b.pdf

Entry: http://read.somethingorotherwhatever.com/entry/Hampton2009

http://chrisvantienhoven.nl/mathematics/encyclopedia-of-poly-geometry

Didn’t know this had been. Looks interesting!!

@zoec and bc of age (with COBOL), they both are perforated languages

I made a guest post at the n-Category Café, thanks to a kind invitation by John Baez! The plan is for it to be the first of a series:

https://golem.ph.utexas.edu/category/2019/02/sporadic_sics_and_exceptional.html