A few days ago I learned about Binet. This time it’s Marin Mersenne who takes the lemonlight — a mathsy frenchman from the early 17th century. I hear he did philosophically musically theological stuff, and some people decided to name a group of numbers after him.

Mersenne numbers are one less than a power of two, i.e. 2n-1. A handful of these numbers are prime, and they’re called…[footnote]Mersenne primes… ?[/footnote]

A cool thing about these primes is that only 49 are known[footnote]As of 3/10/16[/footnote], the highest being 274,207,281 − 1.