Problem 6: Find the Prime

[ghost]

Did you know that between any positive number n and 2n inclusive, there is at least one prime number?

Given a number n, find a prime between n and 2n!

[mpldr]

Question out of curiosity: how has this been proven If we can't see a pattern in primes?

[ghost]

This theorem, called Bertrand's Postulate, actually has a "short and elegant" proof. (I guess it's "short and elegant" compared to something like Fermat's Last Theorem which is over 100 pages long)

[mpldr]

I won't act as if I understand that. But I accept this as "someone smarter said so and other smarter guys did not find an error".

[ghost]

When your screen is only wide enough to fit 14 characters: A multi-line one-liner!

n=int(input())
print([i for i
in range(n,2*n
) if all(not i
%j==0 for j in
range(2, i))])

[mpldr]

Pull the repo and try next-prime/next.html … it will tell you the next prime… kinda.

Imagine some blinking banners on the page as well… I couldn't be bothered to make them yet. Maybe later.