I believe they would both be infringing. The issue here is intent, and the intent of those two numbers are both to be used to recreate the original number. It's

I believe they would both be infringing. The issue here is intent, and the intent of those two numbers are both to be used to recreate the original number. It's not any different than if one website had the first half and another had the second half. The alternative here would be if you could somehow find preexisting content whose intent was not to recreate this number. In that case it's trivial that the only infringing content would be something that told you how to recreate it based on those (eg if you just have a website for each digit that is trivially noninfringing, but a website that links to each of those websites in the correct order is infringing). It's easy to act like this is absurd because of the natural existing of numbers, but the law is generally pragrmatic and not concerned with extreme hypotheticals. You could similarly argue (and plenty have on internet forums) that every mp3 in existence could be found encoded somewhere in pi, which is technically true but absolutely irrelevant in copyright law; if you encode someones content in a novel encoding it's still infringing the other ephemeral protected content.