This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A334891 #17 Oct 13 2023 10:02:21
%S A334891 0,0,3,12,36,84,174,336,612,1044,1701
%N A334891 Number of ways to choose 4 points that form a square from the A000292(n) points in a regular tetrahedral grid where each side has n vertices.
%C A334891 a(n) >= 3*A001752(n-2).
%e A334891 For n = 4, three of the a(4) = 36 squares are (in barycentric coordinates)
%e A334891 {(0,2,1,1),(1,1,0,2),(1,1,2,0),(2,0,1,1)},
%e A334891 {(0,0,2,2),(0,2,0,2),(2,0,2,0),(2,2,0,0)}, and
%e A334891 {(0,0,1,3),(0,1,0,3),(1,0,1,2),(1,1,0,2)}.
%e A334891 The other squares can be derived from these by translations or symmetries of the tetrahedron.
%Y A334891 Cf. A000292, A001752.
%Y A334891 Cf. A334581 (equilateral triangle), A334881 (cubic grid).
%K A334891 nonn,more
%O A334891 0,3
%A A334891 _Peter Kagey_, May 14 2020