5, 13 and 137 are Pythagorean Primes

Alex Bellos discusses how the Incans used knots in string (Quipu) to record numbers.Check out Brilliant (get 20% off their premium service): https://brillian...

Professor Laurence Eaves on Pythagorean Primes - and why 5, 13 and 137 are three of his favourites!?

More on prime numbers: http://bit.ly/primevids

Fine structure constant on sixtysymbols at http://www.youtube.com/watch?v=WlSLIW0gZtk