Ron Graham on imaginary Erdős Numbers. More Ron Graham Videos: http://bit.ly/Ron_Graham More links & stuff in full description below ↓↓↓ Numberphile merch: https://www.numberphile.com/merchandise Calculate Erdős Numbers (and collaboration distance) here: http://www.ams.org/mathscinet/collaborationDistance.html Patreon: http://www.patreon.com/numberphile WITH THANKS TO THESE PATREON SUPPORTERS: Herschal Sanders Lê OK Merli Alex Bozzi Spiked Math Filipe Junqueira Bill Shillito Andrzej 'Yester' Fiedukowicz Stan Ciprian Tracy Parry Micky Baeza plusunim Support us on Patreon: http://www.patreon.com/numberphile NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile Subscribe: http://bit.ly/Numberphile_Sub Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile Videos by Brady Haran Brady's videos subreddit: http://www.reddit.com/r/BradyHaran/ Brady's latest videos across all channels: http://www.bradyharanblog.com/ Sign up for (occasional) emails: http://eepurl.com/YdjL9 Numberphile T-Shirts: null Other merchandise: https://store.dftba.com/collections/numberphile