I'm not sure I understand the infinite loop that is taking place that chrsitianhammer mentions. Would you mind explaining that? Once I understand that I'll be happy to add whatever relevant info to the description.

Hm.. I have no idea why that would happen either. This is the first Kata i've authored, so maybe there is something I'm missing. I'll go over the code tonight and check it out.

Teaching memoization definitely adds to CodeWars, so good job on coming up with this. The only thing I would suggest is to come up with sample test cases for the users so they don't have to try and submit their code to test that they were correct.

Also, as others have mentioned, it would be useful to let users know that they only need to support 1 argument functions.