Blog posts with problems to get your brain going! You get a new problem every fortnight and the solutions are published later.

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_{You may notice some problems are missing... I'm still migrating articles from my old blog.}

Can you prove that there are arbitrarily many primes in arbitrarily big intervals?

This simple problem is an example of a very interesting phenomenon: if you have a large enough "universe" to consider, even randomly picked parts exhibit structured properties.