You could save yourself the trouble by checking the list of available packages.

Additional packages can be requested by creating a ticket in the Codewars runner repository.

Hey @Tenbagger , just returned to this comment thread by accident: glad to see you ended up solving it and thank you for the good etiquette of resolving your own open Issue.

As for your point about the troubleshooting article: is this comment about unsafe blocks a Rust-specific issue? I'm not very knowledgeable about many other languages.

If so, maybe the docs were written before Rust was added to CW supported languages, or it wasn't anticipated during the writing of the article. If you have access to the CW Discord, you could drop a quick message in the #rust channel there - it could end up helping other solvers, or allow a mod to add a note to the documentation.

That's the correct answer for n=250 and n=5 (I've spoilered your reply just so it doesn't give people info about orders of magnitude).

So it seems your code is fine - I don't use Rust so I'm out of ideas, so hopefully one of the site's Rust users can check the tests and/or your current solution.

You can also ask in the #rust channel in Codewars Discord - make sure you state that you have a working solution, so power users know you're not just asking for the solution ;)

Update - there's a post below https://www.codewars.com/kata/5644a69f7849c9c097000073/discuss/python#62b644f28e12f8005894e382 where a user misses a few terms; there's an edge case that appears as early as n=5 that I can see.

Does your code correctly return 890 for n=5 or does it incorrectly return 1025 (or something else)?

The fixed tests are with the first 4 consecutive terms; latter (random) ones might be the ones that introduce the difficulty.

As a consistency check, what do you find for n=250 ?

Which language? Did you try calling your function several times in a row in your Playground too? Read this: https://docs.codewars.com/training/troubleshooting and help us help you.