In 90s Japan, mojibake (wrong encoding detection) was still a problem that was commonly seen, and UTF-8 wasn't widespread yet. So people put some character at the top of a HTML file to force detection in a certain way.

At line 655: "... In a sparse filesystem it will be the sequence of powers of 3, 5, and 7: ..."

So I think this means three = pow(3, 0);

Doesn't explain why it's not 1, 1, 1 or 1, 5, 49.

It does, you're just not paying attention. The comment appears over the function that uses those variables; it's not 1,1,1 because they want to hit 1 only once in the sequence 1,3,5,7,9,25,27,49,81,125, etc.

It doesn't explain why it's not 3,1,7 or 3,5,1, but that's because there is no reason for that.

The full comment in the source explains it fine, but that's not what I'm replying to; who's not paying attention here?

The abbreviated quote I was replying to just confuses things by leaving out critical parts.

When you're using GNU screen or tmux, you notice that the CPU usage of these processes is sometimes notable.

Here's another way to increase your CPU load with apparently doing nothing:

$ cat /dev/zero