7 is the largest prime followed by a cubic number

Re:7 is the largest prime followed by a cubic number by montenegrohugo on Monday September 03, 2018 @05:38AM (#17901512)

Math is funny. There's an infinite amount of primes, and even though we know a lot of them there's still more left (read:infinite). But at the same time, with high-school level algebra we can prove that the largest prime followed by a cubic number is 7.

The proof is really simple, but the fact is quite unintuitive (at least for me).

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Re:7 is the largest prime followed by a cubic number by tetha on Monday September 03, 2018 @04:59PM (#17904835)

That is number theory. Number theory is at the same time extremely profound and very very blunt.

Every prime is double of an integer + 1, except for 2. This follows because primes are integers, integers are either 2 times n or 2 times n+1 and numbers representable as 2 times n have 2 as a prime factor, if n > 1. Hence, except for 2.

Overall, number theory is one example to me how very, very simple concepts are actually hard - because you're not trained to look for them. The proof is just ... obvious once pointed out. But why would you look for it with such simple manners?

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