Tagged: hexagonal packing

A centered hexagonal number, or hex number, is a centered figurate number that represents a hexagon, with an original dot in the center representing the first order hex number, and additional dots added in concentric rings representing successive hex numbers, forming a hexagonal lattice, or packing of circles, depending on your spatial metaphor of choice. In decimal, the first few centered hexagonal numbers are: 1, 7, 19, 37, 61, 91, 127, 169, 217, 271, 331, 397, and so on.