Timeline

This puzzle was suggested by Hugo Pfoertner - thanks Hugo! In a now-famous 2004 article, Ben Green and Terence Tao proved that arbitrarily long arithmetic progressions exist in the primes. This holds true analogously for

Find the greatest prime divisor by stripping factors from the remaining value.

Use the recurrence between consecutive even Fibonacci terms to skip every odd value.

Turn a finite scan into three arithmetic-series sums with inclusion–exclusion.

A cycle-following strategy turns an almost impossible search into a surprisingly hopeful one.

How far can an army of pegs advance when every move must be a jump?

Two missing corners, thirty-one dominoes, and one coloring that settles everything.

One prize, three doors, and an informed host: should you switch?

Nine distinguished points of every triangle quietly share a single circle.

A practical way to search for the quantity a legal move cannot change.