An array of "trees" of unit height located at integer-coordinate points in a point lattice. When viewed from a corner along
the line 
in normal perspective, a quadrant of Euclid's orchard
turns into the modified Dirichlet function
(Gosper).
Euclid's Orchard
See also
Dirichlet Function, Greatest Common Divisor, Orchard-Planting Problem, Orchard Visibility Problem, Visible PointExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Euclid's Orchard." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/EuclidsOrchard.html