This particular set of gears was the result of a challenge by Oskar to Andreas Röver in 2006. Andreas found this nice set of all-primary-numbers gears which is about 0.01% exact.
When Oskar made the Looney Gears, he made the conjecture that there do not exist exact solutions for this type of eccentric planetary gear systems. After seeing Oskar's video of Looney Gears, Bill Somsky proved that there are actually huge numbers of exact solutions for Looney Gears. These exact solutions are now called "Somsky gears". Somsky's discovery and proof showed that Oskar's conjecture (that there are no exact solutions) is wrong.