A spectrum formed by the Lagrange numbers. The only ones less than three are the Lagrange numbers, but the last gaps end at Freiman's constant. Real numbers larger than Freiman's constant are in the Markov spectrum.
Lagrange Spectrum
See also
Freiman's Constant, Lagrange Number, Markov Spectrum, Spectrum SequenceExplore with Wolfram|Alpha
References
Conway, J. H. and Guy, R. K. The Book of Numbers. New York: Springer-Verlag, pp. 187-189, 1996.Cusick, T. W. and Flahive, M. E. The Markov and Lagrange Spectra. Providence, RI: Amer. Math. Soc., 1989.Referenced on Wolfram|Alpha
Lagrange SpectrumCite this as:
Weisstein, Eric W. "Lagrange Spectrum." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LagrangeSpectrum.html