Submitted by Whispss_ on Reddit,
"Alright hi! I was watching a video today on the Cicada 3301 clues and solutions, however the person said there was a clue there was yet to be solved. It goes as follows, "In twenty-nine volumes, knowledge was once contained. How many lines of the code remained when the Mabinogian paused? Go that fair in from the beginning and find my last name." So I went and I searched for a Mabinogian.pdf, downloaded it, and did a highlight search for pause. At about line 255 with around 1242 lines left, might be different in translation, there was the word pause. So when you subtract 255 from 1242 you get 987. From here I went to the first sentence 29 volume book which stored knowledge. This is an encyclopedia. I then went to my bookshelf and opened up the A volume. What then happens took me a good 10-15 minutes to do, and that was count every individual line from A. At line 987 the word is Arthur. Meaning the writers name in Arthur. This is interesting for a few reasons. 1. Arthur mentions King Arthur a few times a few clues back. 2. In context of the Mabinogion the king is the one who pauses. 3. This means the person that wrote has a god complex. TL;DR The guys name is Arthur unless you can prove otherwise."