Nobody knows how to cite 4chan mathematicians who solved an interesting problem

What do you mean by hash? 4chan posts use an incrementing id per board, so if you put >>>/sci/3751197 you have a unique identifier for the post (sci being the board and 3751197 being the post number). For convenience you could link to an archive site as well, but they're known to die every few years.

Drag it through the blockchain then.

Some boards like /pol/ have a user hash, unique per user-session, stable across posts.

For those not familiar with the series in question, there's a reason why, if you're going to choose a TV series to discuss permutations, you'd choose Haruhi.

"The Melancholy of Haruhi Suzumiya" is a 14-episode anime adaptation which aired in 2006. Unusually, it broadcast its episodes not in chronological order, but in a mixed order, but for good theatrical reason; the series comprises a main plot arc, and various self-contained episodes which chronologically occur after it. Rather than have the climax of the series come halfway through, the self-contained episodes are distributed in between the episodes of the main plot arc. It sounds mad, but it actually worked very well.

This idiosyncrasy was explicitly referenced by the episodes themselves: the "next episode" preview at the end of every episode has one of the characters say "The next episode is episode X", then another character says "Wrong! The next episode is episode Y", where X and Y are the numbers according to broadcast and chronological order.

Amusingly the story gets more complicated from here. After the series was unexpectedly popular in the anglosphere, it got licensed for an official release. After the contract was signed and it was too late to change it, the company which licensed it noticed the contract had a stock clause in it requiring the episodes to be released on DVD in chronological order. They were unable to get this changed, whereas the strong fan preference was for the broadcast order. As a partial workaround, I recall they released a special edition with the same episodes on two sets of discs: one in broadcast order and one in chronological order.

But the DVD "chronological order" isn't quite chronological either; one of the episodes is a show-within-a-show, a film made by the characters of the series. This happens chronologically late in the show, but it is the first episode in both the broadcast and DVD order (which makes for an extremely confusing introduction to the series).

So there are at least three different plausible ways to watch the series: broadcast order, chronological order, and DVD order (which is almost like chronological order but not quite). This absurd legacy makes the series rather the obvious choice for discussing permutations of episodes. (My own preference is for yet another permutation: broadcast order, but with the aforementioned first episode moved to before the 12th episode, which relates to it.)

Something I somehow doubt too many of you would know but 4chan, despite being considered an unsavoury place because of certain subsections of it (which I'm not proud to admit I visit to learn what "the other side" is talking about), has a lot of great communities as well and I usually find the discussion quality there better than reddit.

Also, in the context of this thread, 4chan is an ephemeral site so there is no such thing as link to content.