The following image is a much larger version of the table on the wikipedia page for the Legendre Symbol. I sort of like throwing big data at problems like this, or, to express it with greater clarity: the table on the wikipedia page is too small! source code tarball. Quadratic nonresidues are in red. Quadratic residues are in blue (1) or green (0). I wonder if the radial striping also appears in the Hilbert and Artin symbols? Probably could use the attention of a number theorist proper.