The Kolakoski Sequence
Thanks Squarespace: https://www.squarespace.com/numberphile
Full length colouring video: https://youtu.be/a-6oOVdU7Oo
Alex Bellos books (including colouring books): http://bit.ly/BellosBooks
Colouring by Tiffany Arment: https://twitter.com/tiffanyarment (or coloring as it is America!)
Thanks to Loretta Kolakoski for pictures of William (Bill).
OEIS entry: https://oeis.org/A000002
Oldenburger paper (1939) pre-dating Kolakoski: http://www.ams.org/journals/tran/1939-046-00/S0002-9947-1939-0000352-9/S0002-9947-1939-0000352-9.pdf (the sequence is sometimes named for Oldenburger too)