Re: [math-fun] Two questions in geometric combinatorics

On Fri, Jan 30, 2004 at 05:17:01PM -0500, asimovd@aol.com wrote:

Let A_n denote a regular tetrahedral arrangement of points in 3-space, n to an edge. (The layers successively contain 1, 3, 6,... points.)

Can you be more explicit what this arrangement is? I am completely baffled. Peace, Dylan