TL;DR: “Sexy” refers to “Sex” as in, the prefix that means “six,” specifically prime numbers that are 6 apart from each other (e.g. 5/11, 13/19, etc. — more examples are given at the link.
There’s nothing “sexy” about the math, it’s just a play on the word sex as meaning both procreation, and its relation to the number six.
TL;DR: “Sexy” refers to “Sex” as in, the prefix that means “six,” specifically prime numbers that are 6 apart from each other (e.g. 5/11, 13/19, etc. — more examples are given at the link.
There’s nothing “sexy” about the math, it’s just a play on the word sex as meaning both procreation, and its relation to the number six.