I will be going over them again and again, lad, combing for details I can uptake. The only thing I can see which unifies all Carmichael numbers is the criterion that the p-1 of all primes dividing n also divides n-1. That seems to be it. It would be wonderful to find more connections unifying them. There might be some other unifying principle which would significantly lessen the work involved in computer searches for them.
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Several more things to mention. The first is the difficulty of the math now facing us. How difficult for you I do not know, but for me quite difficult are the great abstract fields ahead. There can hardly be enough preparation. I am like a wolf that has been picking off theorems from the outskirts of the herd for years. I rather know what to expect and still find the slogging torturous. Those articles created far more questions than they answered for me. The basic idea of an ideal seems simple enough at first presentation. The idea of a field consisting of multiples of single number such as 2 or 3, is easy to grasp. For instance the even numbers. Every multiplication or addition of any two elements in the field produces another element of the field, a basic requirement of groups. Easy, right?
But then one learns that Carmichael numbers also form an ideal field (my language is not yet straight). And one says, What? I thought ideals were simple multiples of a single number. Carmichael numbers are not multiples of one another that I can see.
So I have a long ways to go to get the basics of this higher mathematics under control. If Category Theory is not higher mathematics, then I do not know what is. If Category Theory is still elementary mathematics, I am, sir, a moslem's uncle. From what I have seen so far it offers the highest and most abstract view available in mathematics. I have been toiling in the grease of the gears of raw numbers for too long. I now must attempt to take the step to the lofty views which dash away whole categories with a few slashes of chalk.