incorrect claims I deleted this Using contemporary computational technology it would take on the order of 10250 years to exhaust all possible 2 colourings of graphs of size 43 However many of these colourings are isomorphic to each other and an intelligent algorithm that only checks unique colourings could get the task done in as little as 10220 years Brute force enumeration ceases to be practical much earlier the number of unique 2 colourings of a graph on 18 nodes is already an intractable 1 788 1030 The main reason is that it is simply not true Nobody would try to look at all possible colourings one at a time as there are much better ways Looking at all colourings is not possible for graphs of size greater than 13 and very expensive for size 13 yet many larger Ramsey numbers can be found exactly via computer search In other words this type of calculation does not correctly indicate the difficulty of searching A secondary reason is that blogs are not permitted as sources in Wikipedia see WP BLOGS