Edit: As an after thought, there are recordings of million digit prime numbers: http://www.primegrid.com/download/SR5-180062.pdf
e.g.,
p is prime 2p + 1 is prime 2(2p + 1) + 1 is prime...
There are no infinite chains, but there are conjectured to be inifinitely many finite chains of every possible length.
i think taglines/subtitles/subject sentences should be eligible for titles too