In 2011, an anonymous anime fan on 4chan posed a puzzle inspired by the series “The Melancholy of Haruhi Suzumiya”:

“What’s the shortest sequence containing every possible order of the anime’s 14 episodes?”

Surprisingly, this playful question turned out to be related to a deep combinatorial problem called superpermutations—finding the shortest sequence that includes every permutation of a given set.

Anime enthusiasts and mathematicians joined forces online, ultimately making significant progress in combinatorics, solving a puzzle that had stumped mathematicians for decades.

https://www.wired.com/story/how-an-anonymous-4chan-post-helped-solve-a-25-year-old-math-puzzle/