A feed of tagged nodes. https://hexnet.org/blog <p> The Tetractys is a triangular figure of ten points arranged in four rows, equivalent to the fourth triangular number. It was considered sacred by the ancient Pythagoreans of yore. </p> Sun, 20 Jun 2010 02:14:14 +0000 https://hexnet.org/content/tetractys https://hexnet.org/content/tetractys <p> 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. </p> Fri, 11 Jun 2010 21:13:51 +0000 https://hexnet.org/content/hex-numbers https://hexnet.org/content/hex-numbers "Graphene is a flat monolayer of carbon atoms tightly packed into a two-dimensional (2D) honeycomb lattice, and is a basic building block for graphitic materials of all other dimensionalities. It can be wrapped up into 0D fullerenes, rolled into 1D nanotubes or stacked into 3D graphite." Wed, 14 Apr 2010 03:03:16 +0000 https://hexnet.org/content/graphene https://hexnet.org/content/graphene