3 ms·

Funnily enough, there is a Wikipedia page with all three letter acronyms, that correctly shows CQK as the first unused one (red link). https://en.m.wikipedia.o

• gwern 3y ago
  Hah! I didn't know that existed. Figuring out how to parse it would be a bit tricky, however... looking at the source, I think you could try to grep for 'title="CQK (page does not exist)"' and parse out the '[A-Z][A-Z][A-Z]? ' match to get the full list of absent TLAs and then negate for the present ones.