==Markov numbers== 
 I didn't understand why you removed the number 610 from the list. This number is contained in , but the wikipedia list now gives the impression that there was no markov number between 433 and 985. It should be possible to find a triple containing the 610, shouldn't it? 
 Moreover, I think your claim "Markov numbers are sums of pairs of squares" is non-obvious, and hence should have a source (or a sketched reason). -