Markov number
A Markov number or Markoff number is a positive integer x, y or z that is part of a solution to the Markov Diophantine equation x 2 + y 2 + z 2 = 3 x y z , {\displaystyle x^{2}+y^{2}+z^{2}=3xyz,\,} studied by Andrey Markoff (1879, 1880). The first few Markov numbers are 1, 2, 5, 13, 29, 34, 89, 169, 194, 233, 433, 610, 985, 1325, ...